Based on this product's specifications, here are some alternatives and similar models
Rear Brush Gearbox Assembly for Roborock vacuum, model 9.06.0160 replacement part
Summary description:
Replacement rear brush gearbox assembly for Roborock vacuum cleaners, model 9.06.0160. This spare part houses the drivetrain for the rear rotating brush, restoring brush rotation and debris pickup when the original gearbox is worn or damaged. Suitable for repair and maintenance to recover cleaning performance and extend appliance lifespan.