I have owned an Osprey 4410 heavy duty scooter for 5 years. It will run over 9 mph on level ground, and according to the manual can go over 30 miles on a charge, but I question that part. Has 13 inch tires which supposedly give it a 7 inch ground clearance, but they were creative in figuring that. I have been having a problem for a little while with it hesitating when I start out, and if traveling at low speed it seems to jerk or hesitate, as if it has a bad gear in the trans-axle. I use this thing a lot, and figured I had better look into it, though I don't think there is much of anyplace to get parts short of buying the entire trans-axle assembly, but I thought I would give it a try.
I removed the housing, seat, etc. and raised the rear up with my engine hoist, and set a stool under the rear of the swing arm and swung the swing arm down so I could remove the motor. I rigged up an adapter so I could run the trans-axle with my cordless drill, and the trans-axle ran smooth and quiet, so my next step was to dig into the electric motor.
That thing was a pain to take apart, and full of carbon dust from the brushes, what a mess. However, when I got it cleaned up, I found the problem, On two of the brushes, the wires were bent over the side of the holder, and were so heavy they were keeping the brushes from making good contact on the armature.
Cleaned the armature, and got it all back together and everything works great. Started at 10:30 this morning, took off an hour and a half for lunch and later supper, and finished at 6:30 pm. Long day, but it works great now.