Kid's Power Wheels parts source
 

Recently I remember somebody in this group was looking for a motor or
other parts for one of those Power Wheels vehicles for kids. I stumbled
onto this site--I have had no dealings with them, but they do list a lot
of parts such as batteries, chargers, motors, gearboxes and wheels:

http://www.mendingshed.com/mendingshed/powerwheels.html