Shade is no longer working, or working intermittently: How to determine whether it is indeed a shade problem or the result of a bad wire connection in the vehicle:

You need to isolate the problem to determine whether it is indeed a shade problem or whether it stems from an
intermittent bad wiring in your vehicle (or a bad dash switch). If a wire in the vehicle wiring is stripped or
pinched by some sharp edges of the metal chassis, you will notice a strange intermittent behaviour by the
shade. The following test shows you how you can find out in few minutes what the real cause of your shade
problem is in order to prevent a situation where you order a replacement shade, only to realize that your
problems persist. First determine what motor types are in your shades then follow the instructions below: 

Motors with Mechanical Limits (2-wire motors) 4280P

Disconnect motor wires and connect them directly to a power source like a battery or a power adapter. The
shade should move smoothly in one direction. If you swap the wires to reverse polarity, the shade should
now move smoothly in the opposite direction. If the shade operates properly, the problem stems from a
faulty vehicle wiring. However, if the problem still persists it is indeed an issue with the motor, but it could
also originate from the limit adjustment: try and turn both limit adjustment screws at least 6 full turns
counter-clockwise. Try the above test again to see whether the shade now works in both directions. If still
not working, replace motor.