Omega 321 and Lemania 27ch Servicing - Resolving the Lazy Hour Register

The Omega 321 and Lemania 27ch can suffer from a problem known as “lazy hour” wherein the hour register increments somewhat, or a lot, even if the chronograph is stopped. The picture shows the dial side of this movement and the parts involved. The hour register is driven off the mainspring barrel and a series of parts leveraging friction and used for activation, stop, and reset provide the hour register capability. Many collectors have learned to live with the lazy hour problem but they don’t need to if the watch is properly serviced. Some watchmakers may assume that this problem can always be solved by eccentric screw adjustment and replacing worn parts. This is not necessarily the case with many watches. There is another factor involved here— replacement parts compatibility and design changes. Omega and Lemania made changes to the dial-side hour parts over the years and disparate replacement parts from past or current servicing won’t necessarily work together as-is— parts incompatibility plays a role. In addition, it takes a good deal of time to test and detect lazy hour, so you need to put a longer than typical test process in-place. We’ve learned through experience that we can often modify incompatible parts to make them compatible if need be. As part of overall servicing, we can eliminate lazy hour and return the chronograph to correct operation.

ClockSavant Omega 321 Lemania 27ch chronograph servicing and repair - addressing a lazy hour register counter