I purchased a clock last fall from a guy in Toronto. It wasn't working when I came to pick it up, but he promised it had been the whole time up until then. He blamed the cold weather, but seemed like an honest guy.
Today I finally rigged it up on a bench and to my surprise it worked. I opened it up and replaced the face with a white one I made. Cut out the old bulb and wired in LEDs. Put it back together... and it was dead. Opened it up again and determined everything was fine except for some friction. Hit it with a penetrating fluid and all is running well now.