Robot reports E3 and stops; side brush does not rotate or rotates intermittently.

Safety first: Turn off the robot and remove it from the dock.

• Remove side brush: Use a screwdriver (if required) to remove the side brush screw. Pull off the side brush and clear hair and debris from the hub and around the motor shaft.
• Inspect the hub: Check for cracks or warping that could cause rubbing against the bottom cover. Replace the Side Brush if damaged.
• Check motor shaft: Ensure the shaft spins freely by hand and is not bent. If stiff or wobbly, the motor is likely failing.
• Reinstall and test: Refit the side brush securely and start a cleaning cycle.
• If E3 persists: Replace the Side Brush Motor Module. This usually involves removing the bottom cover, unscrewing the motor module, swapping it, and reconnecting the harness.