Down on luck newcommer

I just got into RC trucks and so far I am not having much luck. The first one I bought was an off brand 1/8th truck made by Sinyih I like the way it ran but I stripped the spur gear and cant find one anywhere so the motor runs great but it just doesn't go anywhere. So I went and bought a 1/10th stadium lightning 10 but I can not get it to run for more than about 3 min. Then it dies and won't start back up. I don't know much about tuning the motors up, but I can usually make them run half ass ,I had the first one running fine. could someone please tell me what to set the needles at to at least get it started so maybe I can break the thing in. thank you Troy