In this case the previous owner had run his gmaxx with a tight slipper and hit a car tire at full throttle, while during the crash still giving throttle. Since the motor didn't had a chance to get the power away, the shaft broke.
http://i25.photobucket.com/albums/c8...r/125_2517.jpg
If you(Mike or anyone else) want's I can take measurement of the motor/ spool when I get it?