The problem; a run-on strike. The solution; remove the movement, poke around looking for the cause, find it almost immediately and apply a quick fix.
My winter (2017) project was an antique German Junghans Crispi time and strike spring driven wall clock made in the style of a Vienna Regulator. It was manufactured in Schwenningen, Germany in 1899. It came to me as a box of parts. I put hours of work into this project so a malfunctioning movement was a bit of a disappointment.
When I originally disassembled the movement for servicing I made two errors. In my attempt to correct a bent star wheel paddle, I managed to snap it off.
However, I also managed to snap off the paddle wheel arbor spring which is essentially a thin steel wire which maintains paddle tension during the strike. At the time I did not have the right tools to repair the break. Hmm! After a professional servicing, all is right.
Fast forward to 2019
Now, two years later the strike side decided to malfunction. It was striking incessantly. I decided to check out the problem. I took the movement out of the case, removed the clock face and immediately noticed that the strike tension wire had wiggled out of the arbor so that nothing prevented the paddle from stopping, hence the run-on strike. As I mentioned this was one of the repairs made on the clock when it was professionally serviced.
The solution is Loctite. Some purists will scoff but I believe there is place for modern materials in clock repair so long as the repair is functional and discreet. I positioned the spring correctly and applied Loctite where the wire runs into the paddle arbour and allowed it to dry for 24 hours.
After the repair the clock is striking as it should. However, it took me a couple of days to find the correct beat. For some reason this clock must be absolutely level to function correctly. If it is off by just a smidgen it will not run. Anyway, everything is fine now.