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Discussion Starter · #1 · (Edited)
A history of the classic automatic King Seiko, with a comparison of the 5626-7113 and the 5256-8010

This is a slightly updated version of a post I made to the Watchuseek Seiko & Citizen forum a few weeks ago. I have been told that it might be appreciated here - in fact maybe I should have come here first!

My main interest is automatic King Seikos. I focus on the classically-styled models, especially those following Taro Tanaka’s famous “grammar of design”. This was the innovative new style adopted by Seiko in the late 1960s, around the same time that the first automatic King Seiko was produced. In fact, the lifespan of the automatic King Seiko and the heyday of the grammar of design were pretty much contemporaneous. In “A Journey in Time. The Remarkable Story of Seiko” (Seiko Watch Corporation, 2003), Taro Tanaka’s approach to the new style is described as follows:

He started by creating cases and dials that had a perfectly flat surface, with two-dimensional curves on the bezel as a secondary feature. Three-dimensional curves were not used, as a general rule. He also decided that all distortion should be eliminated from the dial, too, so that it could be finished with a mirror surface. This formed the basis for the new Seiko style.”

More precisely, I take this to mean that the grammar of design was characterised by flat surfaces (no curvature) and surfaces with curvature in only one “principal direction” in geometrical terms. For example, the curvature on the surface of a cone has only one principal direction, while the curvature on a sphere is in two directions. The restriction of curvature in the grammar of design gives objects a distinctive look due to the sharp contrast of edges with evenly reflective surfaces, somewhat reminiscent of crystalline forms in nature. I’m fascinated by this style, because it seems to me to represent a fusion of modernism with traditional Japanese minimalist aesthetics as well as a break from certain historically ingrained western design habits (convex/concave surfaces, fluting and scalloping etc.). At the same time, it still somehow manages to look subtle and restrained, the essence of simplicity – quite a trick!

Later on in this review, I want to compare two King Seikos from the mid-1970s, right before the line was discontinued – the 5626-7113 King Seiko, and the 5256-8010 King Seiko “special”. I think these watches represent near-perfection in the truly functional, automatic mechanical wrist watch – the zenith of the art immediately before the complete dominance of quartz. After this, mechanical watches would no longer aspire to represent the state of the art in utilitarian horology. Although they have enjoyed something of a resurgence, the vast majority of mechanical watches sold today are grossly oversized, with a focus on superficial decoration and/or unnecessary mechanical complications rather than on accuracy, compactness, optimal functionality and understated elegance of form.

Before going on to examine these two watches however I want to briefly outline the seven year history of the classically-styled, automatic King Seiko. I am no expert, but I have spent a lot of time looking at these watches and at photographs of them on Japanese auction sites and elsewhere (including case backs with serial numbers indicating year of production), and feel I have some grasp of the progression of the various styles as well as the relative rarity of certain models that does not appear to be documented elsewhere.

I restrict my own modest collecting to stainless steel models and to watches with both day and date functions. For simplicity, I will refer only to movement numbers for day/date models, but in most cases there was also a date-only model with the movement number ending in “5” rather than “6” (often also a non-date version with the movement number ending in “1”, but for some reason these sometimes had completely different case numbers).

Among the very first automatic King Seikos were the 5626-7000 KS and the 5626-7040 KS chronometer. The 562x movements were more finely adjusted and higher beat (8 bps) versions of the lower beat (6 bps) 5606 movements widely used in Seiko’s mid-range watches. The case design of the 5626-7000 was clearly closely based on the manual-winding 45 King Seiko, except that it was a “one-piece” monobloc type opened by removing the bezel and glass rather than a screw-back, and featured an external regulator accessed via a small screw between the lower lugs. The 5626-7040 chronometer had a different case design, also a monobloc type with external regulator, with stubbier, multi-surfaced lugs. These watches have gold case-back medallions. The 5626-7000 seems to have been produced in fairly large numbers for the Japanese market between 1968 and 1971. Here is mine:

There were a lot of other 562x KS case designs from this early period around 1970 (chronometers as well as non-chronometers), many with gold case back medallions. None seem to have been produced in the numbers that the 5626-7000 was however (correspondingly, the 5626-7040 appears to have been the most widely produced chronometer model), and almost none had the same grammar of design aesthetic, instead usually having fashionably 1970s cushion-type or oval cases (e.g. the 5626-5030, 5626-6000, 5626-6020, 5626-7010, 5626-7030, 5626-7070, 5626-7080 and 5626-7099) or square designs (e.g. the 5626-5010 and 5626-5040). I won’t focus on those watches here. More conservative models included the fairly common monobloc 5626-7120 and the later screw-back version, the 5626-7121, which had conventionally styled cases with curved, convex-surfaced lugs, and the 5626-7060, also with a restrained but "non-grammatical" design. Of course there were also the very glitzy 70s-styled “Vanac” KS models, which usually had very colourful dials, chunky hands and hour markers and faceted crystals (but never medallions).

An interesting rarity is the 5626-7100. This watch was a chronometer with a monobloc case and a medallion and with the same movement as in the 5626 King Seikos, but was manufactured for export and thus not actually branded as a King Seiko (the King Seiko line has always been restricted by Seiko to the Japanese market). The case closely follows the grammar of design, and in fact is of a style very similar to the Grand Seiko 5646-7010.

During this period the first King Seikos based on the 52xx calibre were also produced (beware confusion between 56 and 52!), notably the much lauded 5246-6000 special chronometer. Again, the 5246 and 5256 movements used in King Seikos were higher-grade versions of more widely used mid-range movements (the 5206/5216). Between them, the 562x and the 524x/525x movement streams powered all automatic King Seikos made until the line was abandoned after 1975. The 56xx calibre was made by the Suwa branch of Seiko, while the 52xx was a Daini creation. While the two calibres were about equally used in the “Vanac” KS models (the 52xx ones designated “special”), most of the other King Seikos used the 56xx stream, and of the few non-Vanac models to use 52xx movements most seem to have been produced in rather small numbers for short periods and are correspondingly quite rare. As far as I can tell, the only even vaguely classically-styled KS models to use the 52xx calibre were the 5246-6000 special chronometer (not particularly common, but not nearly as rare as it is often made out to be), the 5246-6010 special chronometer (rare), the 5246-6020 KS (rare, and neither a chronometer nor a “special”), the 5246-6060 special chronometer (rare), the 5246-7000 special chronometer (rare), the 5256-8000 special (uncommon to rare) and the 5256-8010 special (uncommon to rare), the latter being one of the two main subjects of this article. There were also some distinctly “unclassical” yet non-Vanac designs with snap-back cases, the peculiar oval-cased 5246-5000 and the rectangular 5246-5010 and 5246-5030 models.

The earlier 5246-6000, 5246-6010 and 5246-6020 had one-piece cases, while the later 5246-6060, 5246-7000, 5256-8000 and 5256-8010 had screw-backs. As far as I know, none of the automatic 52xx series King Seikos ever had medallions. The 5246-6020 had a cushion-type case and the 5256-8000 a rather uniquely shaped lugless case designed specifically for a bracelet, so are not really classically-styled King Seikos. The 5246-6000 with its brushed, convex lugs, arguably doesn’t quite epitomise the style either, despite its iconic status. The interesting 5246-6060 and 5246-7000 had faceted crystals and dark-coloured dials, adding just a hint of "Vanac style" to what are otherwise beautiful examples of the grammar of design. Despite the different case numbers the only obvious difference between these two watches is that the 5246-6060 had a teal blue coloured dial while the 5246-7000's was dark grey. The 5246-6010 and the 5256-8010 were perhaps the best-conforming 52xx calibre King Seikos to the classic automatic KS aesthetic inspired by the grammar of design, which is most prominent in the 562x series King Seikos (not counting the SCVN001 “Seiko Historical Collection Year 2000” KS replica based on the 4s movement, which of course is a direct continuation of the 52xx calibre stream).

Returning to the 562xx series, in 1971 Seiko undertook a major redesign of the case and dial of the “standard” KS 5626-7000 pictured above, resulting in the 5626-7110. For many people this watch is the epitome of the automatic King Seiko. In very superficial terms, the case retains the look of the 5626-7000, although the lugs are more sharply pointed and the side profile is different. The dial was redesigned with narrower hour markers. The hands, however, were the same. The monobloc type case with the external regulating screw was retained, as was the gold medallion in the earlier examples. Here is mine:

It took me a while to get one of these in good condition. The ones with medallions were produced for a rather short period, and while not that uncommon, they tend to either be in poor condition or else overly polished and/or refinished (perhaps because their status as the “classic” automatic KS gives them a high sale value if they appear to look falsely “new”). Interestingly, there is some variation in individual examples in the relative width of the side surfaces and of the very narrow flat surfaces on the inside top of the lugs that does not appear to be due to refinishing – my one is relatively wide in both these dimensions, in that respect being a little closer to the later screw-back designs (see below).

Later production runs of the 5626-7110 and the 5626-7040 chronometer, while keeping the monobloc case designs and case numbers, lost the medallion, substituting an engraved “KS” roundel instead. I pity the poor Japanese businessman, who, probably sometime in 1972, was gifted a later example 5626-7110 or 5626-7040 as a retirement present and discovered that it lacked the coveted gold medallion!

The basic case and dial design of the 5626-7110 was retained for all of the “standard” 562x King Seikos produced until 1975, although there were a number of minor changes made, designated with new case numbers. By far the biggest change (in late 1972) was from the 5626-7110 to the 5626-7111, when the one-piece monobloc case was abandoned in favour of a screw-back design. The case is otherwise practically identical, although in side profile the top surfaces of the lugs slope very slightly less far down, and the side surfaces are correspondingly a little wider (see the side profile of the very similar 5626-7113 below). Instead of the engraved roundel found on the back of the later examples of the 5626-7110, there is simply “Seiko KS” engraved in large letters. The movement was also changed slightly to replace the external regulator with a standard one, with this designated by a “B” on the rotor (5626B) instead of an “A” as on the externally regulated version. At the same time, the 5626-7040 chronometer was replaced with the 5626-7041, also a screw-back design and also otherwise nearly identical to the previous monobloc model, with the same case-back font style as the standard KS 5626-7111.

In the following year, 1973, the case number for the standard KS was changed again, resulting in the 5626-7113, the other main subject of this article (pictures below). In the 5626-7113, the “Seiko KS” in large letters on the case-back is replaced with a simple “Seiko” in smaller letters. This is the ultimate end-point of the trend in the 1970s away from decorative case-backs towards a simple, almost industrial style. I would be very interested to know if anyone has noticed any other changes between the 5626-7111 and 5626-7113. I do not own a 5626-7111, but I have been unable to detect any other differences from looking closely at photographs. The signed crown on the 5626-7113 is slightly different from the one on the 5626-7110, with most 5626-7111s seemingly having the 5626-7113 type(?), although this isn’t entirely clear to me from photographs – perhaps the change in the crown design occurred during the 5626-7111 production run, and of course this is a part that is often swapped in old watches or may even have varied in new ones depending on parts availability at the factory.

The 5626-7113 was produced from 1973 all of the way through until the “end of the line” in 1975. The 5626-7041 chronometer was not updated when production of the 5626-7111 switched to the 5626-7113, and the slightly better finished case back engraving style seems to have been retained in this watch right through from 1972 until 1975. The 5626-8000 and 5626-8001 models, apparently produced contemporaneously with the 5626-7113 in 1975 (and perhaps also late 1974?) are extremely similar to the 5626-7113, seemingly differing only in having slightly different shaped bezels and smaller, lower profile, usually unsigned crowns. These watches are a bit of a mystery. It seems strange that Seiko would introduce new models differing so slightly from the 5626-7113 at the same time as the latter model was still being made (also, what is the difference between the 5626-8000 and the 8001?). As with the differences between the 5626-7111 and 7113 models, I would be interested to know if anyone who owns both a 5626-8000 (or 5626-8001) as well as a 5626-7113 has noticed any other variations.

And so on to the second subject of this review, a comparison of the Suwa 5626-7113 KS and the Daini 5256-8010 KS “Special”. Both of these watches were sold alongside each other in 1975 (although my 5626-7113 was manufactured in 1973). The 5256-8010 appears to have been produced only in 1975, and is correspondingly rather uncommon. Here is how they were illustrated in the 1975 catalogue, where the 5626-7113 was priced at 28,000 yen, and the 5256-8010 special at 30,000 yen. (This compares to 33,000 for a 5626-7041 chronometer, and 47,000 for a basic 56xx series Grand Seiko). Interestingly, in 1975 the really expensive Seikos were the new high-end quartz watches, many of which sold for hundreds of thousands of yen and had case designs that look really tacky and dated to modern eyes – the mechanical GS and KS watches are demoted to half way through the catalogue, although they have kept their looks and their value much better!

From the Seiko 1975 catalogue - the 5626-7113 is on the left, the 5256-8010 on the right:

And here are my ones:

Looking first at the case designs, both watches epitomise the “grammar of design” with their pointed lugs, flat sloping reflective surfaces and sharp edges. The 5626-7113 has the classic KS look with the sloping lugs ending in very narrow flat surfaces adjacent to the watch band, while the 5256-8010, while very similar, has larger triangular surfaces on the tops of the lugs, a style that was also used in the earlier 5246-6010, 5246-6060 and 5246-7000 special chronometers. The 5256-8010 case design appears to intentionally hark back to these 524x calibre chronometers of a few years earlier. Although like them it is a KS “special”, it is not a chronometer. Interestingly however, the “5” in the movement number implies a higher grade than the “4” in the chronometer movement numbers, so there is an apparent contradiction here.

The dials of the watches are practically identical, differing only in their model numbers and in the lettering and symbols below the “KS” logo (“HI-BEAT” and the Suwa logo for the 5626-7113, “SPECIAL” and the Daini logo for the 5256-8010). The hands, however, are subtly different – both are of the dauphine style with thin black lines centrally, but those of the 5256-8010 are slightly narrower and seem to be a little more finely finished. Again, these hands are nearly identical to the ones used in the earlier 5246-6010, 5246-6060 and 5246-7000 special chronometer models. There seems to have been some consistency and coherence to the general styles used by Seiko across their watch ranges, with certain types of case design usually associated with certain types of hands.

One really nice feature of the “special” is the lack of polishing on the lower surfaces underneath the lugs, which instead look brushed. However, I wonder if rather than actually being brushed they have simply been left with the machining marks from an earlier production stage, allowing these surfaces contrast with the polished upper surfaces. This would fit with Seiko’s slightly industrial, high-precision aesthetic.

The “standard” KS, by contrast, is polished on all top and side surfaces. The following picture also shows the crystal in side view, which is considerably raised above the bezel with a bevelled edge – the crystal of the 5256 (above) is lower. Both of these watches have completely flat crystals, unlike the original 5626-7000 King Seiko which had a very slightly domed crystal (the doming is very subtle and it appears to be flat on superficial inspection).

While the 5626-7113 has a crystal attached to a metal ring, this in turn being held in place by the separate bezel, the 5256-8010 has a an integrated crystal and bezel. In daily use, the watches are very similar. Hand winding of the 52xx movements is fairly stiff, so the large crown on this model is a really nice feature. Both watches allow day and date setting when the crown is pulled out to the first position, and hack when it is pulled to the second position. However, whereas on the 5626 movement the day is moved forward by rotating the crown upwards/clockwise and the date by rotating it downwards/anticlockwise, on the 5256 movement this is reversed – clockwise rotation of the crown advances the date, and anticlockwise the day. Furthermore, when advancing the day the mainspring is wound at the same time, unlike on the 5626. The 56xx movements, of course, have the infamous plastic day/date rocker wheel that is very sensitive to breaking if an attempt is made to change the date at night time – fortunately mine is still intact!

If we want to see how these watches really differ, however, we need to look inside. Firstly, I am no watchmaker and have only a superficial (and mostly theoretical) understanding of horology, so I refer readers to articles on these calibres written by the truly knowledgeable. This great article explains the 5606 movement (the lower-beat base calibre for the 5626) in some detail:

While this one looks at the 4s24 hand-winding movement, the 4s series being in effect a continuation of the 52xx series under a different name (obviously the 4s24 itself looks superficially rather different because it lacks a rotor):

Clearly, BOTH of these movement streams are very special! I have worn 5626 and 5256 watches exclusively on a daily basis for several years now (fully serviced of course), and they have never let me down. I have been able to regulate both my 5626-7113 and 5256-8010 to be consistently accurate to within 2s a day, and most of the time they are within 1s a day. The movements are also quite pretty, with their well-finished and distinctive rotors:

Sorry about the poor quality of these photos. Actually, the 56xx and 52xx calibre streams were fundamentally different mechanisms designed and built in-house by two separate branches of Seiko. This is another source of great fascination for me, that the same company could produce two different movement ranges for watches filling almost exactly the same market niche. This is immediately clear from the pictures, where we can see that all of the major parts in these movements are completely different. For example, the 5626 has a larger diameter balance wheel with its bridge on the right, while the 5256 has a smaller diameter one with its bridge on the left. These are not just variations on an in-house theme, they are utterly different movements from the ground up. In fact, even their drive trains are organised fundamentally differently. While the 52xx calibre is an “indirect centre seconds” movement, the 56xx calibre has “direct centre seconds”. An indirect centre seconds movement, despite having a seconds hand in the centre, is organised in the traditional way (dating back to the 17th century), in which the centre wheel (driven directly by the mainspring barrel) is in the middle of the movement and driving the minute hand. The only difference from an old-style watch with a separate seconds hand on a smaller dial (driven by the fourth wheel) is that the central seconds hand is driven indirectly by a dedicated “seconds pinion” that (like the fourth wheel) is driven by the third wheel, but unlike the fourth wheel is outside of the main drive train (the sequence of wheels running from the mainspring to the escape wheel). However, in the “direct centre seconds” movement of the 56xx series, the drive train is completely reorganised, with the centre wheel moved away from the middle of the movement (it is no longer the centre wheel at all!). Instead, the fourth wheel is now in the middle, and the second hand is driven directly by it. Now it is the minute hand that is driven indirectly, through an intermediate wheel. These concepts are explained (and illustrated) very well in these great articles:

So really, these two movements are about as different as they can be, given that both have exactly the same functions and were designed to achieve about the same level of performance in the same type of watch. You can notice the difference in the way the minute hand and the second hand behave. Although direct centre seconds (as in the 5626-7113) is generally assumed to be better because the directly-driven second hand is less prone to “jitter”, I can honestly say that I have never noticed any jitter in my 5256-8010 (or other 52xx series watches), which seem to have just as smoothly sweeping second hands as my 56xx watches. On the other hand (excuse the pun), I do notice that in my 56xx series watches (with the supposedly superior direct centre seconds, but indirect driving of the minute hand), it is more difficult to set the minute hand to always fall exactly on the minute marker when the seconds hand is at 12. There usually seems to be a tiny bit of “drift” for the first few minutes after setting the time until the minute hand settles down. With the indirect centre seconds 52xx movements however, if you manage to get the minute hand right on the minute marker when setting the time, it will continue to track precisely. My (completely uneducated) guess is that this is due to a bit of “slop” in theindirect driving of the minute hand by the intermediate wheel in the direct centre seconds driving 56xx movements. Based on these Seiko movements at least, personally I prefer indirect centre seconds!

I hope that in this review I have managed to convey something of what fascinates me so much about these watches. I genuinely believe that if you want a perfect mechanical wrist watch, you can’t do any better (or find anything more interesting) than a vintage automatic King Seiko. If in good condition and properly serviced, it will be as accurate and reliable as almost any modern mechanical wrist watch, whatever the price. This is partially a product of Seiko’s rigorous and exacting in-house design and production process, and partially due to the period in which they were produced. In the late 60s and early 70s, all of the major technical innovations in watchmaking had already taken place - Glucydur-equivalent balances and Nivarox-equivalent balance springs (Seiko produced their own alloys in-house of course), and more advanced lubricants allowing reliable higher beat movements. At the same time, mechanical watches were still “mainstream”, so their underlying designs were motivated more by the attempt to achieve perfect practical function than the desire to create non-functional mechanical novelty for a purely luxury niche market. In aesthetic terms, by epitomising the “grammar of design”, they achieve a perfect balance between elegance and simplicity, with the sort of subtle, timeless beauty appropriate for an item made to be worn permanently on a daily basis, perhaps for a lifetime. Modern mechanical watches are mostly oversized and over-visible – designed to demand attention rather than to invite it, and more often than not to advertise their cost (actual or apparent) rather than their quality, while at the same time representing a more disposable culture because of their adherence to transient fashion.

Of course much of what I have said about automatic King Seikos could also be said about automatic Grand Seikos and even some of the Lordmatic (LM) models of the same period. The LM range also used both the 56xx and 52xx movement streams (although lower grade versions, and in the case of the 5606 lower beat), while many Grand Seikos of the period used the 56xx stream (others used the 61xx stream). Although the GS 56xx movements were numbered 564x rather than 562x indicating a higher quality and/or level of adjustment, the accuracy it is possible to achieve from 562x KS movements suggests to me that if serviced and adjusted, they are effectively equal to the GS 564x ones. So in this sense, vintage automatic King Seikos may practically be the equivalents of Grand Seikos, but offer better value for money because of the ongoing status of the Grand Seiko label (whereas the KS label is now purely historical).

Finally, I would like to appeal to all those seeking one of these watches to find out as much as possible about them before buying, and in particular to avoid the over polished and re-dialled examples that sadly now have become the norm on ebay. Large volume sellers have found that polished watches with dulled edges and repainted dials sell for higher prices than scratched ones with slight imperfections that nonetheless retain their intended original form. Thus every month, large numbers of these rare watches are being ruined in order to feed this demand. You can only partially blame the sellers, it is equally the fault of uninformed buyers who would prefer to have something that looks brand new over something that looks its age, even if it is completely unauthentic and looks nothing like it would have done when genuinely new. Be particularly careful when buying a watch with a medallion – a number of after-market medallions are available and are often used to replace damaged originalss on refinished watches. Some of these are thinly gold plated and quickly wear down to expose base metal when worn (the original medallions also eventually wear in a particularly unattractive way, but that's a different story!). You can usually identify original medallions from good photographs, but it is difficult to describe how. One clue is the boundary between the edge of the medallion and the case – the original medallions have a narrow, flat margin that sits slightly lower than the edge of the recess in the case and without any gap visible.

I'd love to hear about other people's experiences with these watches, and especially to have my inevitable errors and/or oversights corrected. Sometimes I think I'm the only person in the world with this particular obsession! ;)

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Discussion Starter · #2 ·
stophmaster's pictures of his recently sold 5246-6060

'stoph (stophmaster) recently sold a really nice 5246-6060 special chronometer, one of the rare 52xx series King Seiko models I mentioned above. The case design of this watch has some similarities to my 5256-8010. As the photos are excellent and as this is such a rare watch, I asked him if he was planning to save them for posterity and he kindly gave me permission to copy and post them here.

As I said above, this watch and the very similar grey dialled 5246-7000 are rather unique in being classically-styled King Seikos and yet with a hint of 1970s glitz in the form of faceted crystals and coloured dials. Lovely!

**All images by stophmaster**

**All images by stophmaster**

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Discussion Starter · #4 ·
Thanks for the feedback! Yes, sorry if the volume is a bit overwhelming, I put it all together bit by bit over quite a long time and I have a bit of a close focus on these models. ;)

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Discussion Starter · #6 · (Edited)
Regulating the one-piece case models...

Just a little note on the regulating mechanisms for the 5246 and 5626 movements that have one-piece cases and a screw between the lugs.

The earlier 5246 and 5626, although using completely different movements, both allowed the movement to be regulated without opening the case. However, the mechanism used was different and the way you use it is different.

Firstly (this may not be obvious if you are new to these watches!), the screw you see on the case between the lugs is just to provide access to the regulating screw. Don't try to regulate the watch by turning this. ;-) You need to remove this screw with an appropriately sized jeweller's screwdriver and put it somewhere safe... beware that if you drop it on the carpet there is a good chance you will never find it again!

Now you can find the actual regulating screw on the movement just underneath and turn it with a smaller screwdriver. It helps to see the screw first, which can be quite difficult in dim or artificial light and/or without magnification.

The regulating mechanism for the 5246 is nicely explained and illustrated here:

Note that turning the screw outwards/anticlockwise always speeds up the movement while turning it inwards/clockwise always slows it down. With this mechanism, the screw will stop turning if you turn it too far in one direction, i.e. there are limits in both directions. Obviously, don't try to force it past those points!

The mechanism on the 5626 is rather different, and arguably superior. You can see what it looks like in these photographs (especially the second one):

With this mechanism, turning the regulating screw causes the round part with the off-centre pin between the prongs of the regulating lever to rotate. If you turn the screw in one direction the disk/pin will rotate one way, while it will rotate in the other direction if you turn it the other way. But the important thing to note is that you can keep turning the screw in either direction as long as you want, and the disk with the pin will keep on rotating. This will cause the regulating lever to oscillate backwards and forwards, alternately speeding up and slowing down the movement. The practical upshot of this is that you can't know without seeing the movement whether turning the screw in one direction will cause the movement to speed up or slow down, you just need to turn it a very little bit in one direction and then observe over several hours whether the watch is getting faster or slower. Depending on the position of the disk and pin, clockwise could be faster and anticlockwise slower, or visa versa. Also, once the lever gets all of the way over in one direction (the fastest or slowest setting) it will start to go back the other way, so the directions will be reversed.

Although it sounds from that as if the 5626 regulating mechanism is more fiddly, it is actually rather superior because it has less slop in it and it is impossible to damage it by forcing the screw too far in one direction. In practice it seems to be far easier to regulate the 5626 than the 5246 as the relationship between how far you turn the screw and how much the speed changes is more consistent.

In both movements, the external regulating mechanism only allows a little bit of fine-tuning (perhaps 15 seconds or so per day difference in speed?), so it relies on the watch being fairly accurately adjusted to begin with. Otherwise you may find that you can only adjust it to be more or less fast or more or less slow...

Finally, don't over-tighten the outer screw on the case when replacing it or you risk damaging or splitting the tiny gasket (if you still have one!)
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