Meshing your gears is more than just sticking paper between the gears. This is a good trick for spacing the gears, but does not line up CB and spurgear. When you set up your gear mesh can you roll your buggy freely with little or no sound coming from the CB and SG area. It sounds likeyou have a good spacing but your engine is not squared up. Do you use rubber seal or steel? I used to blow the rubber seal CB bearings a lot. I live in south Florida, and on a 95 degree day you can burn up bearings. I have been using the Kyosho steel seal and have not had that problem. On a normal race day I go through a set of bearings by the end of the day. 4 hours of practice and 3 hours of racing will blow CB bearing in hot weather.

I also was wondering is your inner or outer bearing or both?