Well, check the mesh between the cb and the spur. That is the only reason it could strip. YOu can find directions online about how to mesh the spur and cb. Also, after diff break in, if you have done as the manual says to, tighten the diff a lil every few tanks. That will save it, even a plastic one. Initially, the hobby sucks, I learned that the hard way w/ my parents not to happy either. But now I have 2 evaders and I love it.