You can download the schematics at...
http://www.rainvac.com/rainbow-vacuum-schematics
Russell Ruckman, June 2013
It is a simple induction motor. Uses two replaceable brushes. UNPLUG THE UNIT 1ST!!Check the armature for wear out. Is the switch working? Use a VOMeter to check it. Ground should ALWAYS be CONTINUOUS. Do not test it with any current on, it could ground on you and cause injury. Check the continuity of the cord with the meter.
Chances are that the brushes are maxed out.
jeff VA, December 2008
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I can answer this question...
How do I rewire a Rainbow Vacuum Cleaner Model D4C?
