Most separate Power Nozzle motors in Rainbows and other vacuum brands are not 'user friendly' so as to make them worthwhile in time or cost for overhauling. They are sealed up pretty good, and usually very difficult to get apart. If the brushes, bearings, bushings, or armature are shot, the motor is generally not worth fixing. The motors are meant to be tossed and replaced. Labor cost to repair the motor, exceeds the cost of a whole new motor.
(I'm referring to the separate power nozzle motor that turns the belt that drives the brush roll, and not the larger motor in the main vacuum cleaner itself).
LR, May 2008