Original Poncho parts are hard to find..Don't know if there is an OEM kit or not..
If it is just the motor that needs renew, and the armature is still good, you can get bearings and Brushes at the home center..you have to pull the old ones out And go to the small motor repair box (for like drills ect..) and match the brushes..they usually have an organizer box full of different sizes there..
The same applies to bearings, they usually have small bearing selections there.. you should be able to match one up..
Clean the brush pickup with a light Emery Cloth, clean out the insulator pads between the pickups and reassemble..It should run like new..
If it's a transmission issue..best I can offer, Is Evil Bay..or Craig's list, or places like year one..for a working replacement.