It worked!!! I went slightly a different route, but same theory. I put a checkvalve in-between the center flap vaccuum element and the switchover valve block. I gave it a little vaccuum and connected the two ends together. Presto! I've got my center vents back! I uploaded some pics on another site. Check them out.....

http://www.mbworld.org/forums/showthread.php?p=1262037#post1262037