DIAGNOSIS A partial blockage in the dustbin's emptying path or a full/defective dust bag. The grinding noise is the dock's motor struggling.
FIX Remove the robot from the dock. Take out its internal dustbin and empty it manually. Inspect the robot's emptying port on its rear and the corresponding suction port on the dock for clogs of hair or debris. Remove the dust bag from the dock, check if it's full, and reseat or replace it. Ensure the bag is installed correctly, not folded or obstructed.
IF THAT DIDN'T WORK The issue may be the dock's internal filter. Remove the dust bag compartment. Locate the small foam filter. Take it out, clean it under tap water, let it dry completely for 24 hours, and reinstall. A clogged filter severely reduces suction.
HEADS UP Never use the dock without a dust bag installed. Debris will enter the internal motor, causing permanent damage and voiding the warranty. Only use official or compatible bags that fit snugly.