Originally Posted by dogenia
His main problem is that he keeps melting his spur gear adapter which means that the car wont move forward.
Additionally now the front differential only spins on one side under load. As long as the diff is outside the car it functions as it should but as soon as you put it inside the diff housing and close everything up the front left wheel of the car does not spin when power is applied.
Spur holder is simple there is supposed to be a pin behind the adapator - I suspect it has fallen out and been lost or the screw has come loose and the pin dropped out. if it's melted you will probably need to replace.
The other problem check the plastic housings they will crack if you get a good hit and the diff will bind - if it is broken check the A arm pins as well as they bend as well.
Or it could be the diff have you pulled it apart and checked it the drives only run on the plastic and can wear.