New to the RC world. I bought my son an ECX AMT MT and the servo quit working after he was running it for a while. Case heated up and motor quit. I picked up a 25 kg from the local hobby store after installing and getting everything set up I could not use the arm that was supplied as it was to long and hit on the body of the vehicle. I installed the original arm and bench tested all steering works as it should. When he starts to give it throttle the steering is intermittent and stays turned when returning to centre or won’t turn at all. If you run it very slowly works as it should. Any thoughts on what has gone wrong?