I repaired this Seth Thomas Adamantine mantel clock made about 1902. The movement was very dirty, and had a broken time mainspring. Instead of being broken in one place, it was in 22 pieces!
The broken time mainspring – 22 pieces!
Improper cleaning can cause multiple mainspring breaks. Someone may have cleaned the movement without taking it apart. This can leave cleaning fluid on the mainspring. The cleaning fluid little by little eats into the spring, weakening it.
Repair job 6239. I replaced the strike mainspring as well as the time mainspring (given the broken time mainspring, I didn’t trust the strike mainspring to last long). I polished the pivots, installed 16 bushings, and straightened one arbor (gear shaft).
New Mainsprings:
Time: 3/4 by 0.0160 x 120 inches. Timesavers no, 15959 (the new type with a copper rivet).
Strike: 3/4 by 0.0163 by 120 inches. Timesavers no, 15959 (the new type with a copper rivet).