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Discussion Starter #1 (Edited)
So I rarely have to do this but I am asking the collective SCWF watchmaking community for help troubleshooting and diagnosing an issue that I am encountering with a recent service I did on a 69 Seiko 6139-6010 Proof with 6139A cal movement for a fellow SCWF member.

The watch runs strong as evident by the amplitude numbers I am getting on the Timegrapher and keeps good time but I continue to get signal line degradation after about 12 hours of run time. I have narrowed the fault down to something in the escapement. Visual inspection of the escapement components under 30X bifocal microscope magnification does not show anything out of the ordinary from my perspective. The balance wheel, hairspring and impulse jewel look good. Impulse jewel is seated vertically and tight. Pallet fork and stones show no visible signs of wear. Escape wheel looks okay visually but this is where I suspect the fault.

Here is what I suspect is the issue and why. For those watchmakers in the know or having experienced this phenomena please chime in with your thoughts and recommendations. As you can see in the first two TG traces, I am getting great amplitude and a relatively clean straight TG line with no fallout of signal degradation. These two TGs were taken last night around 10:30PM with full wind on the MS and after having cleaned the pallet and re-lubricated with Moebius 9415 on the ends of the pallet stones. I also was able to snake a bit of Rodico in while I had the pallet out and touch and clean up the escape wheel teeth. Reinstall the pallet and balance and fire the movement up and everything looks great after a bit of regulation.



After 8 hours of run time, still have good amplitude but you can see the degradation of the TG line which gets ragged and shows some knock and fallout.



My suspicion is there are a few bad or worn teeth on the escape wheel and when run with fresh lubrication on the end of the pallet stones this lubrication masks any knock or fallout due to the bad escape wheel tooth or teeth and thus a clean line. As lubrication disburses and thins out on the pallet stones and escape teeth over time the signal degrades and gets ragged with some fallout points or knock.

I am interested in opinions from those watchmakers in the know and would appreciate any other tips on how to fix or resolve the issue outside of what I have already tried. My next step would be to purchase an NOS escape wheel and install it and see if this resolves the issue. Are my suspicions correct and will the NOS escape wheel resolve my issue? Thanks for your assistance and interest.
 

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I agree with your theory. Most likely a bad escape wheel. The wheel and the teeth are very small and any wear isn't visible to the eye with a loupe. You would need a microscope to detect the wear and if there is wear you will have to replace the escape wheel. There are charts available on the web that will help with reading the tracks you see.
 

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If you can extend the timebase, you might be able to pick out the fault more easily, by matching fault regularity with interval.
There's a Witschi manual in the archives, with 'scope and trace fault examples.
 

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Discussion Starter #10
Okay folks, got this issue figured out. Through deduction and some luck I suspected the escape wheel was bad due to the fact the watch would run well with fresh 9415 on the pallet stones but once that lubrication ran in overnight and thinned out the TG line became ragged with some fallout. Upon inspecting the escape wheel under 30x bifocal AMScope I found what I would describe as some small areas or spots of scale on a few teeth; the kind you might see built up on a faucet fixture. I figured this was creating a rough surface for the pallet stones to engage and disengage with resulting in the ragged line and noise. Installed a new NOS escape wheel part 251-612 for cal 6139A and the watch is running like a champ now.


TG on full wind:

TG after ~10 hrs run time

TG in the Case:

 

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Great detective work John and a beautiful watch!
 
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