RE: stampede spar gear kepts going bad
you must have a differential in the gear box. unless you changed it for a positrack. a car without diff is really squirly and uncontrollable on track unless you like to do donut all the time. and no stock car are coming that way at my knowledge
if your car doesn't move even without the spur, you need to take that gear box apart and see if you have something broken in it.