Based on this product's specifications, here are some alternatives and similar models
Replacement main brush gearbox for Roborock S8 S8+ S8 Pro Ultra Q8 Max Q5 Pro Q5 Max — gear assembly
Summary description:
Replacement main brush gearbox compatible with Roborock robotic vacuum models S8, S8+, S8 Pro Ultra, Q8 Max, Q5 Pro and Q5 Max. This gearbox transfers motor torque to the main brush to restore rotation after wear or failure. Intended for repair and maintenance, it helps recover cleaning performance, avoid full-unit replacement and extend the vacuum's service life.