Replacing a Mason-Sullivan Clock Movement

July 21, 2019 2:32 am Published by Leave your thoughts

Replacing a Mason-Sullivan Clock Movement

Replacing a Mason-Sullivan Clock Movement only requires the most basic tools. A pair of needle nose pliers and both styles of screw drivers is usually all that is required for the swap out. The new clock movement will be the same movement you have now but brand new, so all fits the same as it did. Having a Mason and Sullivan clock movement puts the movement 40 years old. The company went out of business this long ago so it is time to swap it out. It worked night and day for 40 years with out too much complaint, the new one will do the same.

The disguise

The Mason and Sullivan company from MA USA built and sold countless clock movements and clock kits. So many they were able to convince the makers of these units to have there name stamped right on the movements. Not long after that they even had there own numbering system put in place instead of the makers numbering system.

The Availability

Although they are now out of business we can still replace the clock movement. The movements were not their own anyway and the movement producers are still in business for the most part. The German manufacturers are making the same movements as they did 40 years ago in other words. A new movement will last longer than even the very best overhaul by the best clock maker. The movement would be half the price of even a cleaning on the old unit and be brand new instead.

The Identification

The first step is to ignore any names on the clock movement and only pay attention to the numbers. Match the numbers on the ID page to see who made it. It may or may not have a M/S number on the back plate itself on the low right. If it is a M/S numbering system it would be followed by an X at the end of the number and you would go straight to the conversion chart. It will say something like 3325X or similar. This is if your clock movement has the Mason Sullivan number system only. As explained the exclusive M/S numbers were used only in the later years. Prior to this it would have the M/S name and the real makers numbering system. If you do not have an X in the number it is most likely a Hermle movement and you would need to go to that web page to match it up.


The clock movement is most likely a Hermle movement in disguise. The new unit can ship the same business day if ordered early enough, comes oiled already. It will have its chains or cables and pulleys if its a floor clock movement, comes with instructions and support to install the unit.

The content of this website is copyright by Clockworks and written by James Stoudenmire

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