RE: breaking in motor with gearbox
I use a lot of them and don't break them in. If you want to water break in putting the gearbox in won't hurt it, just dry it off after your done with a heat gun or hair dryer and put a drop of light oil in the bearings. If you don't want to drown the gearbox the motor's face mounted with two small phillips screws, remove them and pull the motor out. Retiming it's more beneficial than breaking it in, loads of info in here on retiming.
Mike