I have a rovan baha ext 5ts with the 45cc engine. I was the running the car and all of a sudden it stopped moving. The motor revvs out but will not move under a load. If I pick the wheels off the ground everything moves as it should. I pulled both rear dog bones out and the pins on the dog bones and the wheel hexes are in tact. Where should I look next for a problem. I have never torn this car down being that it only has less than an hour of run time on it. Spend more time fixing it than actually being able to drive it.