Hi , I just finished this project on my 300e 87.

1. You removed the glove box.
2. Fix the pink bob ( good)
3. Used an allen wrench to undu the Flap control on the center vent?
4. Got the darn thing our of the way ? There are 4 clips and you will need 2 small flat screwdrivers to lift them and tug at the same time to remove each side.
5. Inside the duct is the flapper control that the allen screw went in.
6. further back on the bottom is another flap. Don't open that one or place anything to keep that one open.

7. That skinny little flap at the back is the one you want to prop open.

That will get you air. $ 900.00 OMG

If you have patience and a cooler place to work the center damper was 34.95 at the MB dealer . That was the easy part

I just got my 87 so I was up for it for over a few nights and using some pieces of wood to prop the dash cover up for my hands to fit. I removed the whole dash pad and replaced the damper. It was a major undertaking yet very simple to acheive to be honest. We were in a heat way of around 98 with heavy humidity so it took me a bit longer and I did it few hours at the time.

LEt me know if you need more help