I did not create this model, please reference the link provided. I typically print a new drive gear every 6 months as they periodically get grinded down by litter getting spilled into the mechanism. Typically only the drive gear needs to be replaced, but attaching a full set just in case.

Replacement motors are available for about $11/ea on eBay. I have a JST kit to clip the wires and put on JST compatible headers for a full motor replacement too. I've replaced both motors after about 3-4 years of use. They will eventually wear down.