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Some times it comes down to: (although we'd rather it didn't) it's been cleaned, lubed, + serviced. The beat error is ok and it's keeping good time. The only issue is low amplitude. You've gone above and beyond the call of duty trying to address the amplitude with less then positive results. If the customer had to pay by the hour they would have drawn the line a week ago........

The fact is that it's capable of being a good daily wearer and a watch is only meant to keep good time.............:)

With all that in mind we go nuts wondering what's up and continue our pursuit of Insane Perfection............. That's why we're WISer's
 

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Hey Simon, you are in deep on this one and it sounds nightmarish. One last thought. I think you stated you jeweled the ports on this movement. Did you cycle the movement with the pallet and balance out of the movement to see how the gear train is operating under some load from the mainspring? Not sure where you are sourcing the jewels you use for repair of the arbors but I know I have some and there are slight tolerance differences, Some jewels I have are tight on the arbor and other less so. I have to trial fit mine to the arbor before installing them just to make sure there is enough tolerance to allow the mainspring to rotate freely. I know you are meticulous in your work. Any burs on or around the arbors on the MS barrel that could be hanging it up? Everything on center so the barrel is not tipped or binding in the arbor ports? End shake on the MS barrel? Have you tried slightly loosening the upper train bridge screws just to see if amplitude improves when this is done? Let me clarify doing this for testing purposes only, not as a solution to the issue.
 

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Discussion Starter #23
Now .... before the big reveal (and there is one - that's the purpose of this thread) does anyone want to have a last guess at what the cause of the issue was (on the basis that no one has yet identified it in the posts above this one).

Let me quote Sherlock Holmes:

"How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?"
 

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Now .... before the big reveal (and there is one - that's the purpose of this thread) does anyone want to have a last guess at what the cause of the issue was (on the basis that no one has yet identified it in the posts above this one).

Let me quote Sherlock Holmes:

"How often have I said to you that when you have eliminated the impossible, whatever remains, however improbable, must be the truth?"
Love that quote my dear friend
We are all waiting to hear the great news
God Bless,John

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Making Popcorn !!!!
 
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Let me guess: you forgot to adjust the lift angle on your timegrapher from 52 degrees to 54.5 degrees...........lol
 

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Oooh, I’m in just in time. You wound the mainspring wrong in some way??? Or it broke partially in the barrel? Based on your epic drama masterpiece here I would expect that the answer lies in the origin of the power for all mechanical watches, the main spring.


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Discussion Starter #29
Sorry if I missed it, but how were your escapement checks? How deep is your locking? Balance amplitude is directly correlated to this.
I'm still at the level of correcting faults in the gear train by replacing parts. I have given some consideration over the last 18 months or so to investing in a Bergeon 2229 Escapement Tester, which if I understand its operation correctly allows the pallet stones to be adjusted in situ, very very accurately as it heats the pallet fork and thus softens the shellac enough for the stone to be moved.

However, I don't think I am proficient enough to actually determine if a stone needs adjusting. I have thought it might be useful for when a stone is loose and just needs the shellac to be re-heated, but I figure its a big investment for something such as this. When I do encounter a loose stone I currently replace the pallet forks.

In this specific case the issue was not down to this.
 

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I'm still at the level of correcting faults in the gear train by replacing parts. I have given some consideration over the last 18 months or so to investing in a Bergeon 2229 Escapement Tester, which if I understand its operation correctly allows the pallet stones to be adjusted in situ, very very accurately as it heats the pallet fork and thus softens the shellac enough for the stone to be moved.

However, I don't think I am proficient enough to actually determine if a stone needs adjusting. I have thought it might be useful for when a stone is loose and just needs the shellac to be re-heated, but I figure its a big investment for something such as this. When I do encounter a loose stone I currently replace the pallet forks.

In this specific case the issue was not down to this.

When I have to move a pallet jewel it's because it's moved/loose so I scrape off the shellac, make sure it's in the correct position - usually it can be seen where it was and I check it indexes correctly and I put a little glue on it. Fixed.
If it's a common movement - replacement is often easier!
 

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Just read this thread.

Looking a your timegrapher readings the fist thing I would be trying to sort out is that one impulse line is straight and the other is fluttering on the timegrapher. This can only happen and the end of the train, so escapement, pallet and balance. Whatever is causing the flutter could also be draining power and reducing the amplitude. I would have replaced all 3 (plus the pallet bridge) to begin with and then starti adding one of the original parts at a time to see what's causing the flutter.
 

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Discussion Starter #32
Nearly time for the big reveal, but before that this is a picture of the original movement (i.e. no replacement parts) after I had realised what the issue must be, rectified it and rebuilt it:




stable, and a very healthy amplitude (don't worry about the BE, this was almost immediately after rebuilding with me just relieved to see that amplitude). Nothing was done to any of the parts that I hadn't already done 6 days previously when I first rebuilt it (bar fixing the one issue).

All of the suggestions you guys have made about possible/probable cause were tried by me very early on in the troubleshooting process.
 

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Popping more popcorn with DAHASCO...


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I love Sherlock Holmes, and I love popcorn. Knives out was a great film.

And, I don't have a clue what's wrong with the patient..........

I'll get my coat too!!
 

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Discussion Starter #40
Here we go then guys. It's the main event. Now, I know that I could have just said what I'm about to say at the very start, but hey it's my party and I certainly did cry along the way.

I decided to write this post because what I discovered (eventually) was something that I would never have thought could be at fault. But, now I know I know, and I will definitely be checking for this going forwards. And, I thought I'd share.

I have serviced a LOT of 6139's. And, I have always sought to get the best performance post service. But, there are a LOT of variables - in fact the more you think about it, its a wonder these 50 years olds run as well as they do.

And, I think as we've seen in this thread that its very easy to fall into a certain mindset for troubleshooting. That of over thinking/complicating the problem. I know I did.

So ................ what was the problem?

take movement A - it runs with very low amplitude
swap out every component until you have movement B - it also runs with (the same) very low amiplitude

what do movement A and movement B have in common?



Well, the only part (except the screws) that I didn't swap out was the centre wheel bridge.

I did arrive at this conclusion myself - once I'd put my deerstalker on. Elementary.

So I took another look at the centre wheel bridge. It looked great (they always do!!). No rust, no damage, a clean jewel, no cracks - but wait a minute, lets have a look on the underside. Hmmm - should the jewel be proud of the plate?

And that was it.

The centre wheel bridge jewel was displaced. Not enough to bind hard on the centre wheel - this is the first thing I check after fitting the bridge and before and after placing the mainspring barrel. But, maybe it was enough to impede rotation?

So, out with the Seitz jewelling kit (one of my best investments), and I press the jewel back to where it should be.

Now at this point I wasn't 100% sure this was the issue - but I had a gut feeling I was on to something.

So, I rebuilt the movement, again (for some reason I'm hearing this said in the voice of Forrest Gump).

And bingo. Immediate amplitude at 225 and climbing. It settled to around the 245+ mark.

So, if you ever have a movement that should run well, because you know it should. And its running with a substantially lower amplitude than it should. Then check the centre wheel bridge jewel ..........
 
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