Welcome to the world of used rcs! Nice character, but buying used is a crap shoot at best, sometimes everything turns out great, sometimes they don't. Perfect for maybe 1 lap.....

I don't have an SC10, buit do have a Slash and based on my experience with a Castle Sidewinder/5700 yours sounds overgeared. I ran mine on stock gearing like 18/86 and it ran hot, but tolerable temps. I'd try smaller pinion if it still works and if motor is indeed shot, call Castle, they have a flat rate repair on the motor for $45, just the time to get it in/out of their system.

http://www.castlecreations.com/suppo...te_repair.html