I accidentally pulled the shaft out by 10mm while removing a stubbon pinion, mine is a Castle 1515 so it's not limited to cheaper motors.
What I did was strip the motor clean it up and added a drop of bearing retainer on the shaft and pushed it back into place, the shaft has a flat spot so the rotor can't slip while turning. This was 6months ago and it's still running, although it's had only 8-10 packs through it...
So if you have experience rebuilding motors, it could be an easy fix?