https://youtu.be/RS1z1BAymCY
In this video I go over some upgrades, maintenance and repairs on a iRobot Roomba 650.
These are the parts I have used:
iRobot Roomba 650 Vacuum (https://amzlink.to/az03aiVgbgfw4)
Side Brush Motor Gears (https://amzn.to/2fTNX8X)
Side Brush Motor Gears (eBay affiliate): http://ebay.us/TyWwuU
Replacement Brushes (https://amzlink.to/az0izyAEZrIVD)
Lithium Battery (https://amzlink.to/az0WwBXRwnCuX)