ok this is quite hard to explain but basically when i push brake on the radio the brakes won't move. i don't know why though but i do know that if i loosen that little gold nut on the side of the carburettor the brakes work again (only problem with this is that the throttle arm thing wont grip and turn the carburettor) so i don't think its a problem with the servo or batteries. what could it be ? any ideas would be helpful.