[nighterfighter]

If you take the motor OUT of the gearbox, and connect it directly to a battery (assuming it is a 12V motor and safe to do so), does the motor turn?

If so, then the problem is in your gearbox. Is your gearbox assembled correctly? Did you grease the gears?

Is the gearbox designed to turn slowly?

Edit: I'm assuming the gearbox is NOT the gearbox provided in the KoP for the kitbot. If it is, then disregard the last question.