I recently worked on this Zenith 146D. It’s a charming two-register movement and well made, as you would expect from a manufacturer such as Zenith. It was probably made in the early 60s, and is in really excellent condition considering its age. Take a look at the end for the watch cased up.

The crown was missing from the watch when it arrived and you can see that at lot of dirt and dust can work its way through what seems like a very small gap. Flecks of dirt were everywhere on the movement.

Here is an example of extra cleaning that must be done after the components have been through the cleaning machine. Some stubborn corrosion and oil reside left behind which needed to be manually cleaned away. If this was left the clean oil would immediately be made dirty and could lead to more wear over time in this critical part of the watch which endures a lot of stress anyway.

Some marks on watch movements are normal and to be expected from use, for example the plating wearing away on the plates where the two winding wheels touch. Wear here is inevitable but can be reduced to a minimum by careful application of oil.

An example of marks not caused by wear an tear are scratches on the top plate; these ones have very clearly been caused by past repairers using unsuitable tools to put the column wheel jumper into place. It’s not hard to use pegwood for this job which will leave no marks behind, and should be standard practice.

Once the chronograph mechanism is fully reassembled the watch can be tested as a complete movement before being cased up for a final test period.