Thanks for the replies:
The reason the push button control unit didn't work, was because the push button control unit was bad. I replaced it with a used one.
Of the vaccum controllers, all were replaced. I got two used and bought a new one. I made sure the use ones were the ones "somewhat accessible" ..... I tested all the used ones several times and all look to be pretty new.
Before assembling the dash, I carefully isolated wires and gave it a test with the battery hooked up and coolant flowing. The good news: the flaps and vacs and buttons now all work .... the bad news: the heater leaks! (I had thought the problem was the O-rings but it turns out it is both the O-rings and the core. I found one locally for $80.
SOOooooo now pull the unit once again, replace the heater core inside and reassemble in stages. Do my partial assembly check once again if good, start closing the dash up.
It isn't as bad a job as it looks, just takes time and patience.
'03 E320 Wagon-Sold
'95 E320 Wagon-Went to Ex
'93 190E 2.6-Wrecked
'91 300E-Went to Ex
'65 911 Coupe (#302580)