Do search on'line. There are many companies that sell clock mechanisms. Try www.klockit.com or Amazon or you might even try Hobby Lobby.
Michael's, Hobby Lobby, www.rockler.com.
Michaels, JoAnns, Hobby Lobby, At Home all sell clock parts
I just saw some at Hobby Lobby
Vicki.....Some jewelry stores may have them. Call some that have been in business a number of years...they sometimes are more likely to be able to help even if they give you a name of someone who works on clocks. Good luck
Amazon has them too plus you can pick up a used clock on the cheap and use its guts