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This 1940's Cyma WWW vintage military watch had a broken balance staff, both top and bottom pivots. This video shows how I removed the old balance staff and replaced it with a new one.
The principle tools used on this job are a Bergeon Platax tool for removing the old staff and roller, and a staking set to rivet the new staff onto the balance wheel and re-seat the roller and hairspring.
The method of poising, which is not shown in the video, is "Dynamic Poising" which is done with the balance in the watch working with enough wind to achieve 100 degrees of amplitude, then measuring the rates with the watch in different vertical positions. This allows me to find the heavy point and adjust as needed.
The end result was a +70 year watch keeping time to within 10sec/day.
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Watch repairs and services in the UK