For now, I would get a new motor. I'd suggest a Trinity P2K or a Reedy MVP. For future reference, do the following on your motors in the future:
1. Cut the comm every 5 runs. If you don't have a lathe, your LHS or a racing buddy can do it for you.
2. Change the brushes when they are severely discolored, pitted, or otherwise just plain look bad.
3. Don't over or under gear. If the motor gets hot quickly or the comm turns orange, red, or purple, you are geared incorrectly.
4. Make sure everything is clean. EVERYTIME you run your motor you should spray it out with motor spray.
Hope this helps.