How are your drivetrains shaping up?

For some reason our drill motors are tripping the breakers really really badly. We don't seem to be able to get any torque out of the motors cuz once the robot stops on the ramp, it's next to impossible for it to start moving up again without tripping the breakers. The robot doesn't weigh all that much (we're at least 50lbs under limit)
And the motors seem completely unresponsive for the first few degrees of input from the joystick.

To add insult to injury...it's overheating.
There's a familiar smell of burning after a few minutes of run time.

Did I mention both motors had their brushes pop out?