Aside from making sure your gear mesh is good (there's a how-to on HPI's site), and checking that the screws that bond the motor plate to the transmission are tight, you're good to go.
To check the screws; flip the truck upside down, and look for the two screws at the back side of the center transmission case. If they're loose, they'll allow the motor plate to flex enough to strip the spur. If they came loose, replace them with a 4-40 screw and nut setup.