If you pull that small gear off and reinsert that woodfuff key it will operate fine. I'm concerned that there are two of them. That motor has less than 90 minutes run time on it.
That small gear is held in place with that key. I'm not sure if you'll need a removal tool or not. Loosen that standard screw, remove gear, set the key in the slot and reinstall the gear and retaining screw.