Remove the gear unit assembly and rotor from the floor buffer's housing.

The gear unit assembly is fitted tightly into the housing. You will need to wiggle the assembly back and forth with a good amount of pressure to knock it loose.

The gear unit assembly and rotor are very heavy, so it may help to support the assembly from the bottom as you remove it.

Re-assembly tip: When installing the new gear unit assembly, make sure the screw holes line up with the housing's screw holes.