So I bought a Matrix Magnum high torque long motor & put it in my gun w/ an M120 spring. The pinion gear stripped within 50 shots. I knew this was a possibility bc some reviews mentioned this but others reported pulling M140s with no issue. The shimming of the gears isn't perfect but it's good enough to where this should NOT happen. So... My question is should I send this thing back or replace the pinion gear for something that can actually work? If you think replace I'll need to be pointed in the direction of which one to get and how to replace it. Thanks in advance!