The front wheel is dirty.
Switch the robot vacuum cleaner off. The switch is located on the side of the robot vacuum cleaner. Depending on the model, press the I/0 switch to switch position 0 or the ON/OFF switch to switch position OFF.
Check whether the front wheel, the cover or the slot recess have become dirty.
Remove any threads and hair, and clean the front wheel, the cover and the recess:
Place the robot vacuum cleaner upside down on a level, clean surface.
Unlock the cover and remove the front wheel.
Remove any threads and hair and clean the front wheel, the cover and the slot depression using the cleaning tool.
Refit the front wheel and close the cover, making sure it clicks into position.