I seem to hit a bad lot of magnetic switches as well, after a few weeks/months of working the switches would become permanently magnetized and cause to clock to rewind into itself. After a bit of tinkering I decided to add a simple metal ball tilt switch to the paddle, seems to be working just fine. Although I did have to use very thin wire so it does not interfere with the paddle's movement. This should have far less chance of failing as it fully relies on gravity now rather than magnets being in the correct position and a delicate glass switch that stops working when cracked.
At some point I might modify the paddle to hold the switch at the correct angle, but at the moment the blue tack seems to be doing the job (and I don't feel like soldering those thin wires again if I can help it).