Nissan Repair: 1998 Quest GXE passenger power window does not operate, mechanical aspects, master switch

Question
My passenger power window stopped working.  If I let the car sit for a few weeks it will work for a minute or two.  I started troubleshooting it and thought I's start by taking the door handle off to find a broken switch housing.  Strange, I know.  I replaced it.  Still no dice.  I then took the door panel off to see if I was getting power to the window motor.  Strangely, I get 12-14v on one lead when the switch is in the up position and likewise on the other lead when the switch is down....BUT THE DARN MOTOR STILL DOES NOT WORK!  I took the window and the regulator etc... out and tested the mechanical aspects of the window.  It goes up and down fine on the track when the motor is unbolted from the regulator.  What could be the problem?  My hunch is a poor power or ground connection...good enough to test 12v with meter but not enough to run the motor.  What is your thoughts?

Answer
Kevin,

If the motor works and you replaced the switch on the passenger side door would mean the master switch is defective.  But, since you say there is power in both up and down, floating ground, you should have a defective motor.  Take it out and use the car battery and wires to check it.  But, from what you say, the brushes on the motor are gone and it will need replacement.