Bet you didn't know many american made clocks prior to 1830 had wooden gears and movements. Here is an example of a movement that needed several repairs to broken gear teeth. In the course of use and due to age individual teeth will break off. This was one of the old clock makers jobs replacing broken teeth. There are a number of methods available to repair this type of damage. Whole gear replacement is one option, or cutting a slot in the damaged gear to add in wood and reshaping a new set of teeth are options. In this case I decided to try a newer approach, using clay a cast of a good section of gear teeth is made and then placed over the damaged area. The missing tooth section is then filled with a mixture of two part epoxy and saw dust. I find this to be the least invasive approach as you retain the original part and only modify it to the extent of replacing exactly what is missing. Pictures show the process and result.