This particular clock is a good example. The clock in the photo is almost always found with either a broken mainspring or a broken alarm spring, and unfortunately parts for this clock are generally not available. Even if they were, you almost have to destroy the movement just to get to the mainspring. Since this particular clock had a broken mainspring, it was a good candidate for a quartz movement.
I began by disassembling the clock and removing the old movement, saving only the clock's body and face. A normal quartz movement is too large for this clock, so I used a movement made to fit a round 2 inch hole. I removed the quartz clock's hands, bezel, and face, and glued the movement to the old clock's original face. I then installed the quartz clock's hands (the original clocks hands would not mount on the new movement).
Once finished, I now have an unusual vintage clock to add to my collection that keeps perfect time!