I know that it's fairly common to not have air coming out from the center vents. But in my case, air ONLY comes out from EVERY vent except the center ones, but under every pushbutton setting! Defrost, Bi-Level, etc. The car is a 1982 300D turbo with the late model climate control (Temperature wheel and 5 horizontal buttons).

The pink vent dampers do receive vacuum and do hold it. I just don't know what's up with them. The pushbutton unit has been rebuilt, so I doubt that's the problem. Thanks for any advice.