I have a Arrma 1/10 Raider and have recently installed a Hobbywing EZrun motor and a new stock differential. It was running ok for a while but then stopped with only intermittent power. When I disconnect the motor from the drivetrain, the motor runs fine, but when installed it jolts back and forwards. Any thoughts on torque problem with the motor or a diff problem? I've taken the diff apart, and can't seem to find a problem with it. And if it is a torque problem, is there any fix other than a new motor?