Pic 1: Then I slipped the square rubber piece back into the housing and test-fit the adjuster assembly. When I was satisfied that the square rubber piece was the correct thickness, I squirted a small dab of caulk (any will do) in the hole where the screwhead was to sit, slipped the repaired adjuster assembly through the hole in the housing, then closed up the flap.
Pic 2: A little dab of ABS cement (Oatey ABS cement, available in the plumbing section at Lowe's) was used on the flap to 'weld' it back in place, then small clamps were used to hold everything together. A piece of a plastic bag was used so the clamps didn't become part of the mirror as that would be bad. These were allowed to set-up overnight.
Pic 3: The next day, a small dab of silicone caulk was applied at the base of the rubber adjusters. This pic was just before application, but I used it sparingly. Doing this, the adjusters are firmly mounted, preventing vibration of the glass, yet flexible enough to allow movement as the mirror is adjusted. I let that set-up overnight as well.
Pic 4: Then the next day I took the completed mirrors and popped them back into my freshly painted housings, and here's the result.
In Conclusion:
The total cost of the repair was ~$3.00 including what little paint I used.
Total time to repair was only ~ 1 hour for each mirror.
Most importantly though, I've got power mirrors again!
Thanks for looking!