Passenger Side Window

1999 Ford Windstar, 110,000 miles, 3.8L

The window motor on the passenger side works and will lift and lower the window. However, it stops working. It will work again if I remove the motor and reinstall it (again, it will stop working after a few hours). Neither the driver's or passenger's switch will raise or lower the window when it stops working. I have also replaced the fuse.

When it does work, the window seems to lift and lower with ease.

Thank you,
Chris