Rear Bulkhead/Arm Support
 

Hope this mod hasn't been posted already.
When I was installing my bearings I noticed that there could be a minuscule rubbing issue causing friction, which could be robbing precious power.
Looking at the photo you can see where I trimmed the plastic so the output shaft and dogbone won’t rub.
Do this to both sides.
I used an exacto knife to shave the notches out. A dremel would have been quicker.