Crashed my Mini 4 Pro yesterday into a tree branch during a windy day. When slowly rotating the motor by hand, I hear grinding sounds and feel periodic sticking, indicating damaged bearings. The motor still spins but feels rough compared to the others. The motor bell and bearings can be replaced by removing a screw/C-clip on the bottom of the motor, then removing the motor bell to access the press-fit bearings. Has anyone successfully done this repair on the Mini 4 Pro specifically? Looking for guidance on bearing size specs and proper removal technique.

Spin each motor by hand and listen for gritty/grinding noises - debris in the bearings is common. Motors are technically waterproof due to enamel coating, so you can spray compressed air on windings followed by warm water rinse. Try cleaning first before bearing replacement.

I had the exact same issue with my Mini 3. If grinding persists after cleaning, the motor has internal issues and needs replacement - desolder the three ESC wires after removing heat-shrink tubing. Honestly, for the Mini series, complete motor replacement might be more cost-effective than bearing surgery.

Be extremely careful with those tiny C-clips - they love to launch across the room! Watch for carbon fiber delamination on arms during motor removal, those splinters hurt. Use proper anti-static precautions and magnetic parts tray. The bearings are usually 2x5x2.5mm but verify before ordering.