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I've ran out of ideas & tricks ...... Help !!


Hello Gents;

I ran out of ideas & tricks.

The movement on my desk is a 1950's New Old Stock LACO 503 with 16 jewels. I came as a none-runner, but the movement seemed okay.


I stripped it, cleaned it and assembled it; it ran, but barely. (See walkthrough:https://www.watchrepairtalk.com/topic/9705-servicing-laco-503-501/

Assuming old oil was the culprit; I stripped it again and stepped up my pegging game. Pegged every jewel and pivot hole. I even pegged the tiny balance-pivot-jewels under the cap-stones. Pegged every wheel-pivot, but not those thin balance-staff pivots: that was too risky for me.

Checked all wheel teeth, pivots and jewels, couldn't find anything wrong with them. Inspected the pallet-fork jewels and impulse jewel; all seem fine.

Installed the balance on the main plate and it oscillated freely. I checked the position of the impulse jewel to the banking pins; spot on, right in the center. Hairspring nice flat, horizontal and concentric.

Installed the pallet fork on the main-plate and it rocket freely on its own weight. Installed the balance wheel to check the engagement with the pallet fork and a little pulse against the fork jewels sent the balance-wheel off, oscillated freely, rocking the pallet fork backwards and forward. Removed both parts again.

Installed the spring barrel, wheel train and bridges. The slightest touch to the barrel teeth and the escape wheel took off. Installed pallet-fork and with a slight tension on the spring, the pallet fork needed only a slight encouragement to "jump" over.

Assuming that this movement was good when it left the factory, one would expect that this movement would now run nicely ....... not so. Not at all !!

It still has a huge beat error (but perhaps the timegrapher picks up another "resonant"-sound?) , a low amplitude (assuming a 42 degrees lift angle) and it even stopped on me a few times ......


I've no idea what to check or what to do next ..... !!??? :(

If this movement was a "lime" when it left the factory, what can it be?? Given the fact the the wheel-train runs smooth, the pallet-fork rocks freely on its own weight, the balance-wheel oscillates freely; why does it run so poor?? (there is no cannon-pinion on the other side to interfere)

Any help or tips are very welcome ........


Edited by Endeavor

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Well i have to say this was a really fascinating read! So much to take in and learn here! Unfortunately i have nothing to add here except to cheer you on.

Will be interesting to follow and see if you manage to get it running as it should.

The best of luck to you with this watch!

Edit: on second thought i did read about a fellow with a similar problem a couple of weeks ago that had to re set the jewels for the pallet fork on a 75 year old watch. Would be interesting to see what would happen if you used the parts from watch 1 and assembled on main plate for watch 2. I dont know if its to any help but i guess anything is useful at this point?!

Edited by Muligans

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6 hours ago, Muligans said:

Would be interesting to see what would happen if you used the parts from watch 1 and assembled on main plate for watch 2

Has been tried, but no difference. As soon as I have time and absorbed all the new information above, I will continue. I first wanted to get an USB microscope up and running, in the hope that I could study the escape-mechanism (and each individual part) better; that's done now; 

Now it's down to the study, so I get to know / understand better where to look at .........

Edited by Endeavor

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Well you could with the balance assembly removed manually actuate the pallet fork with a pin to observe how it locks and unlocks.if it is hanging up you will see where and how.

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@yankeedog; thank you for your suggestion ;) I know this thread has become very, very long, but we've invented a name for this check after Rodabod's idea: "The paper tissue trick". If you go back to page one, you'll see it being born :biggrin:

So far it's not clear to me whether the draw and lock is as it supposed to be. That, and more, I have to cover in my upcoming investigation.

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