Diagnosis
The failure of the Edge-Sweeping Brush on the iRobot Roomba i3+ EVO is typically caused by one of three things: mechanical obstruction, gear failure, or a motor burnout. Most commonly, long hair, carpet fibers, or thin threads wrap around the axle of the brush. Because the i3+ uses a friction-fit gear system, these wraps create enough resistance to trigger the robot's internal "stall" protection, which cuts power to that specific motor to prevent the circuit board from overheating. To confirm the cause, you should first check for a "Side Brush Obstruction" error message on the iRobot Home App. If the robot is reporting the error, it is likely a debris jam. If the robot continues to clean without reporting an error but the brush remains stationary, the issue is either a sheared plastic gear inside the motor assembly or a complete failure of the DC motor. You can test this by gently flicking the brush with your finger; if it spins freely with zero resistance, the gear is stripped. If it feels completely locked, it is a jam.
How to Fix It
Follow these precise steps to clear the mechanism and restore rotation:
- Power down the unit completely by pressing and holding the CLEAN button until the light ring goes dark.
- Flip the Roomba i3+ EVO upside down on a flat, clean surface.
- Locate the yellow Edge-Sweeping Brush. Using a Phillips #2 screwdriver, remove the single screw securing the brush to the chassis. Keep this screw in a magnetic tray, as it is small and easily lost.
- Pull the brush assembly straight up and out of the socket.
- Inspect the axle of the brush. Use a pair of precision tweezers or a seam ripper to cut through hair and strings wrapped around the base of the bristles. Ensure you remove the debris that has migrated *under* the plastic cap of the brush, as this is where the most friction occurs.
- Check the drive socket (the hole in the robot where the brush sits). Use a can of compressed air to blow out any dust or grit that may be preventing the gear from engaging.
- Reinsert the brush, ensuring it seats fully and flush against the chassis.
- Tighten the screw firmly, but do not over-torque it, as this can crack the plastic housing and cause the brush to wobble.
- Power the robot back on and run a "Clean" cycle to verify the brush is rotating.
If That Didn't Work
- Replace the Edge-Sweeping Brush: The bristles can sometimes warp or the internal plastic hub can crack, causing it to slip on the drive shaft. Purchase a genuine iRobot replacement brush (Part # 1711541) to rule out a mechanical failure of the brush itself.
- Check for Gear Stripping: If the motor hums but the brush doesn't move, the internal plastic gear has likely sheared its teeth. This requires replacing the entire side-brush motor assembly. This is a modular part that can be swapped by removing the bottom cover of the robot.
- Perform a Hard Reboot: Occasionally, the firmware "locks" the motor after a series of stalls. Hold the CLEAN button for 10 seconds while the robot is on the dock, then remove it from the dock and start a new cycle to reset the motor controller.
- Inspect the Charging Contacts: In rare cases, low voltage from a degrading battery can cause the robot to disable peripheral motors (like the side brush) to prioritize the main vacuum motor. Ensure the battery is fully charged and the contacts on the Clean Base are clean.
Heads Up
- Avoid using "aftermarket" brushes with stiffer bristles; these create more torque resistance and are significantly more likely to burn out the side-brush motor.
- Clean the side brush every two weeks. Hair buildup is cumulative and puts constant strain on the motor even if the brush appears to be spinning.
- Never use water or liquid cleaners on the brush axle; if debris is stuck, use a dry brush or compressed air to avoid causing corrosion in the motor socket.
- If you have high-pile carpets, the side brush may occasionally stop spinning by design to prevent the robot from digging into the carpet fibers.