[neurokinetik]

Swapping magnets without removing the armature is tricky, but it is doable. You have to pop the little spring clip loose on one side, then use a paperclip with a tiny hook bent on the end to pull the magnets out. Doing this with Neo magnets really sucks, as they usually go flying right back into the motor.

It isn't your imagination, the comm is actually "stuck". There are tiny little tabs on it that stick into the rotor and force it to neutral timing. When you twist, you actually break these little tabs off. After you are done, you can put a drop of superglue where the comm meets the rotor if you want to ensure that it doesn't move. It is much easier to adjust timing with the armature out of the motor, but it really is best to avoid pulling the pinion if you don't really have to. The easiest time to adjust timing is when winding a motor. You can just set it, glue the comm, and wind the motor with the timing already advanced.