Thanks for the pic Cap'n!
I have now completed my floor vent quest! Everything operational!
I discovered that the 86' is unique to other w124 models because it has two vaccum servos that operate the floor vents. When one has a leak, it stops the functioning of the other because lack of vaccum suction. After the one unit was replaced problem solved. It was only necessary to remove the center climate control unit, and front side floor carpets for this job.