Thanks for posting this - it is indeed what this green 124 diy'er needed. I asked about this the other day and was told that the blower was under the wiper arm, but not having the CD and being unwilling just to take things apart for fear of thrashing the entire weekend, I punted.
I happened to visit the MB dealer in town yesterday to get a couple of keys made (sheesh, what an escapade!), and the parts guy showed me the exploded picture of the blower assembly. It looks exactly as you describe.
Screwdriver in hand, I'll be out in the garage this weekend ripping and tearing the skin off my knuckles.