ITS NOT WORTH IT
nobody in their right mind would spend money to fix up a cheap $300 generic made toy
its engineered and designed to have a normal engine life of about 10 to 12 hours of running time, then the engine locks up, the engine metal melts down, cracks, deteriorates, then its junk, you can't buy parts for it and the way its assembled its almost impossible to tear down.
then when its junk and can't be fixed you wasted all that money you put into it