Are you sure that you are not having a problem with your drivetrain? Does the truck roll easily with power off? You must be getting a hell of a lot of resistance from something to continually strip out the spur gear. If you are stripping spurs that easy then I would suspect that something in the setup is screwy. Are you using a slipper or a clutch setup? If you are using brushless power then get some metal drivetrain parts installed (including the spur), and that will give you the strength you need to endure whatever punishment you throw at the beast. Good luck with that

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