This Roamer cushion model was in need of a service. It did run for a little while but it almost immediately stopped again.
The owner sprayed it with WD40. I already scolded him and he did apologize for this horrendous act 😉
Seriously, that’s not a good idea. WD40 attracts dirt and dust, it clogs bearing jewels and it makes the windings of the hairspring stick together. Sticking hairspring windings will cause the watch to run erratically and much too fast, like severe magnetism.
The movement is an MST 264. This is one of the bigger movements with 12 ligne.
Looking at the (lack of) shock protection, this is an earlier model. Circa late 1920s or early 1930s.
Disassembly
Remove any power from the mainspring. Hold the crown between your thumb and index finger and let it slip while you move the click away. You can use an old oiler or a pair of tweezers to move the click away from the ratchet wheel.
Remove the balance and the pallets.
Lift the cannon pinion at the bottom plate of the movement. You can’t lift the center wheel if it’s in place.
Remove the ratchet wheel and the crown wheel and lift the barrel bridge.
Lift the wheel-train bridge and remove the escape wheel, the 4th wheel, the 3rd wheel, and the center wheel.
In this particular case, the bridges of this three-finger wheel-train bridge are all separate. Later MST movements (and Buren movements, for example) have similar looking bridges but they are 1 piece.
Lift the main barrel.
Turn the movement around and start with the bottom plate.
Remove the motion works and the keyless works. Don’t forget the balance capstone.
Pre-clean all the grease with Rodico and the bearing jewels with a peg wood.
Then, clean all the parts in the watch cleaning machine.
Assembly
Start with the main barrel and the wheel train.
Fit the separate bridges/fingers of the wheel-train bridge.
Replace the barrel bridge, crown wheel, and the ratchet wheel.
Turn the movement around and start with the motion works and the keyless works.
After I reassembled the keyless works, it didn’t function well when I tested it.
Then I compared the movement with the illustration in the parts sheet.
So…I had the return bar upside down. Stupid!
Normally, you’ll notice it immediately if something isn’t right. It won’t fit or you have to use force.
In this case, I noticed nothing. The return bar worked but not as it should have.
Flip the movement to the top plate and fit the pallets and the balance.
Normally, I’d polish the crystal but it was too far gone so I simply fitted a new one.
What do you think of this Roamer? Do you have a similar one? Let me know in the comments below.
