Repairing a Sega Toys Deathstar
Why drive belts are used is to reduce motor noise in tape recorders & vinyl belt drive turntables at higher revolutions per minute RPM's at the motor axle.
plastic spur gears also transmit tooth noise, however at the lower RPM's plastic gears will do as the gear tooth noise is below the lower limit of human audibility.
plastic gear grease is also used reduce gear tooth noise, as well as lubrication.