I just bought a Tamiya Double Gearbox kit and two of these motors for it. When assembling I accidentally put one of the pinion gears on a standard motor and one on a replacement motor. Is there any hope of removing the pinion from the standard motor, or am I going to have to buy an RM3 motor just for the pinion gear?
It’s definitely possible to remove the pinion gear without damaging it, and it should still press-fit onto the replacement motor very well. Just make sure you don’t try to grab the gear by the teeth with anything hard like pliers which will crush it and make it useless. You only want to apply force to the bottom circular surface of the gear, the one towards the motor.
If your fingernails are a little on the long-ish side right now you might try just pulling it off from below the teeth with your nails. I just did that on a Tamiya motor to make sure I wasn’t fooling myself and it worked fine, but different batches of gears may vary. Failing that, try to find something with a narrow slit (just barely bigger than the motor shaft) you can slip under the gear to pull it off with. Looking around my desk I’m thinking of using the flat side edges of a staple remover.