If I understand what he is saying when he swaps the plugs on the receiver the throttle works fine with the steering wheel on the TX but when he tries the steering with the throttle trigger on the TX the steering does not work. So I am guessing everything is set properly. Not for sure but guessing as I do not have it here in front of me. So I am guessing a good chance the servo is bad and might not be the gears as there is an electronic board in there that tells the motor what to do in the servo. Things like this are not easy to figure out when not right in front of you! Now correct me if I am wrong about any of what I am trying to say.