the self-emptying base on my combo j9+ is making a horrible loud grinding noise when it empties the bin.

Diagnosis

The loud grinding or high-pitched shrieking noise during the emptying cycle of the Roomba Combo j9+ is typically caused by "vacuum cavitation" or motor strain. This happens when the high-powered suction motor in the Clean Base cannot pull air through the system because of a partial or total blockage. When the motor spins at maximum RPM but cannot move air, it creates an unnatural vibration and a grinding sound as the impeller struggles against the pressure vacuum. This is most commonly caused by a "plug" of compressed debris—such as clumps of pet hair, cardboard scraps, or wet dust—that has become lodged in the narrow throat of the Clean Base or the robot's internal extraction port. You can confirm this by observing the robot during the process: if the robot vibrates excessively or if the emptying cycle takes longer than the usual 15-20 seconds without actually clearing the bin, you have a physical obstruction causing the motor to overwork.

How to Fix It

Follow these steps to clear the airflow path and silence the motor:

1. Power down the Clean Base by unplugging it from the wall outlet to prevent the motor from engaging during cleaning.
2. Remove the robot from the base and press the release button to slide out the dustbin. Inspect the bottom of the bin for the rubber flap valve. If there is debris stuck in the seal, use a toothpick or small brush to clear it so the flap can open fully when the base suction hits it.
3. Open the Clean Base's front door and remove the disposable dustbag. Carefully inspect the cardboard collar where the bag attaches to the base; if this is crushed or misaligned, it creates a bottleneck.
4. Use a flashlight to look directly into the suction port of the Clean Base (the hole where the robot's bin connects). If you see a clump of hair or a piece of plastic blocking the hole, use a pair of long-reach needle-nose pliers or a flexible vacuum hose to extract the debris.
5. Check the "throat" of the robot. With the bin removed, look at the internal port where the bin seats. Ensure no debris is lodged in the gasket area.
6. Reinsert a fresh, genuine iRobot dustbag, ensuring the cardboard tab is pushed firmly into the slot until it clicks.
7. Plug the unit back in and run a manual "Empty" command via the iRobot Home App to verify the noise is gone.

If That Didn't Work

• Check for "Bag Leakage." If the dustbag has a small tear or is not seated perfectly flush against the intake, air leaks into the system, causing the motor to fluctuate in pitch and create a whistling or grinding sound. Replace the bag with a brand new one, even if the current one isn't full.
• Inspect the Base Gasket. There is a rubber seal around the intake port of the Clean Base. If this seal is pinched or torn, it can cause turbulence and vibration. Use a damp cloth to clean the seal and ensure it is seated flat against the plastic housing.
• Perform a Hard Reset. Occasionally, the motor controller can glitch, causing the motor to pulse rather than run smoothly. Hold the "Clean" button on the robot for 20 seconds while it is docked to reset the communication link between the robot and the base.
• Clear the Robot's Exhaust. If the robot's internal filters are completely clogged with fine dust, the base motor has to work twice as hard to pull air through the robot's chassis. Replace the green high-efficiency filters in the robot's bin.

Heads Up

• Avoid using generic third-party dustbags. Non-OEM bags often have different porosity levels or poorly fitting cardboard collars, which restricts airflow and puts unnecessary strain on the suction motor.
• Never vacuum up wet debris or liquids with the Combo j9+. If moisture enters the Clean Base, it turns dust into a "mud plug" that is nearly impossible to remove and can permanently damage the motor.
• Check your dustbag every 2-3 months regardless of how full it looks; compressed dust can block the airflow even if the bag has physical space remaining.
• If the grinding noise persists after all cleaning steps, it may indicate a failing bearing in the base motor, which requires a professional replacement of the base assembly.