[Tristan Lall]

There are three spiral spring pins inserted into holes around the circumference of the gearbox, near to the motor. Each is about Ø0.093 in, and 0.188 in long, if I remember correctly. Using a small punch (or even the back end of a small drill bit in a drill press), press each of the pins into the gearbox. It should then come off easily, and the shaft and planet carriers will come out.

You're probably not going to like the motor pinion that you find inside, though. I'm not sure exactly what it is, but it's got very small teeth.