Limit of the atwood motors?

[Clanat]

Team 753 had an interesting thing happen to our robot at PNW in the finals. One side of our robot wouldn't move at all. Upon removal of the drill motor, the problem was quickly spotted: the plastic drill transmission was shattered. Thinking that was the only problem, we took our timeout and removed the drill motor, just leaving our atwood motor in there running solo. With just an atwood, we still would have been able to maneuver our way to the bar, and maybe even do some pushing on the way. We removed the drill motor in time, and put the robot on the field, but when the match started, the robot still only had 1 side working. The original problem was the atwood motor broke; I'm not sure how, maybe it was 9 straight matches, but the atwood was completely locked up, and the drill motor destroyed it's transmission trying to push it. The atwoods were extremely hot when we took the robot out of the arena as well. I'm not entirely sure which problem caused which, but it is likely the atwood motor.

Is there any particular reason for this kind of catastrophic failure of the atwood motor?