Balance end shake puzzle

[rduckwor]

An Elgin 673 movement that came to me as a non-runner. Cleaned and lubricated. It will run moderately well only in the dial down position with the cock sitting partially down on the steady pins.  Seating the cock fully results in a non-runner.  I have had the balance complete off the cock and cleaned the jewels and end stone well.  No chance of reversing the stones as these are secured by screws and fixed settings.  Pivots look fine under magnification and were well pithed. Testing the balance when assembled, there appears to be zero end shake.  It puzzles me as to how the movement might have come to this state.  Pretty heavy cock to have been bent somehow.  I will try shimming the balance cock to see if that improves it's function.   Ideas very welcome.

 

Thanks,

RMD

[vinn3]

you can find out how long the balance is by shimming the balance cock till it has ample shake.  the proper repair is shortening the balance staff,  but the problem may be with the jewels  or   the former owner.    good luck,   vin

[anilv]

Parts for older watches may need some final finishing... I think watchmakers back in the day accepted this as part of the repair process!.

Another thing with watches made in the 50s is that there were both 'shock-protected' and 'non shock-protected' watches of one particular calibre and sometimes these required different size/length staffs. Somebody could have attempted a repair and gave it up as a bad job when the part didn't fit..and it ended up with you!. For all you know the balance may even be from a different watch!

I would first of all observe the balance roller jewel and pallet fork interaction..the balance roller should sit in the pallet fork without touching the safety pin. If you're satisfied with that then go ahead and see if a metal foil shim works.

If the roller jewel sits too high in the pallet fork then you have to shorten the balance staff to bring the balance lower. On some watches it is possible to drive the balance jewel setting deeper in the plate to achieve the same thing but googling the Elgin 763 I don't believe it is possible as the end jewel is screwed to the plate (maybe you can shim the end jewel?).

Good luck!

Anilv

[rduckwor]

Thanks to both of you for advice.  The case back bears no indication of service, but then, had I left this movement in this condition, I would not mark the service as well.  Thanks, I will work on it and report back.

RMD