Truck Forums - Electric Mirror Crazy Problem

I have a 2000 Sierra with electric side view mirrors (Not Heated & No Turn Signals). One day the switch didn't work at all. I took it apart and cleaned the contacts under the rubber diaphragm. Then only Up and Left worked (both mirrors). I cleaned it again and had all functions for a day. Now, only Up and Left work. It is the style with a rectangular Left-Right rocker above the square tilting directional switch.

I bought a junkyard's "Used & Tested" switch. It does the exact same thing. I traced the wires, looking for a break. (That wouldn't make sense, because it is left and right mirror, but I looked anyway.) I also did the contact cleaning thing on it.

I tested the wires and found good 12 volts on the orange and 2 negatives (all from the window switch blocks). At the left mirror I have:
Yellow: Positive 12 volts when the switch is pressed Up & Left
Negative 12 volts when the switch is pressed down and left
Green: Positive 12 volts only when the switch is pressed down
Negative 12 volts only when the switch is pressed up
White: (Connects to Blue @ Mirror Tail):
Positive 12 volts only when the switch is pressed right
Negative 12 volts when the switch is pressed left.
All Wires: There are stray voltages all over the place when any switch direction is selected. They range from 1 to 5.3 volts.

It seems as though the switch will not only send power to the selected mirror, but reverse the polarity for directional control. I can't get a hold of a wiring diagram and the switch has an evil circuit board inside that I can't access for a peek without destroying the switch.

I get the same results with the new switch and my old switch. I can't believe that the "Used & Tested" switch and the old switch have the exact same problem. Conversely, I think it is the switch because no wires are damaged, it is common problem to both mirrors and it worked fine for a day after it failed. I suppose these switches fail a lot because used ones are difficult to find.

Before I spend a bunch of money on a new (not returnable) switch or another "Used & Tested" switch; do any of you have experience with this problem? Is it a common symptom?

Thanks very much!
Paul