I am getting absolutley nowhere with the replacement of the blower motor in my 1993 300E2.8, and it's driving me crazy.

I'm using the directions as listed on the official Mercedes-Benz CD manuals, the missing procedure 83-040 turned out to be 83-140 "Removal, reinstallation of air inlet cover". In section B, "as of 04/93" (as my car was made in June 1993), step 5 lists 'unscrew screws 549 and remove center divider".

However, on my car, the divider isn't removable. It's fastened on either side to other pieces of insulation and has tubing threaded through it in at least two places and doesn't seem to be removable. Without removing it, I can't get to the next step. The diagram in the car does seem to be of a different engine, the 3 litre, not the 2.8 104 engine, plus on the 2.8 litre car, there appear to be electrical cables running between the (allegedly) removable portion, that isn't mentioned in the manual.

At this point, I have two questions:
1) Has the design of this part of the firewall insulation changed between the 3 litre and 2.8 litre versions of the two cars and if so, what are the changes in the procedure to remove the air inlet cover?
2) Is this part exchangeable by a novice but well-prepared DIY'er, or should I just have the dealership replace it when I have the 150K service done next week?

Any ideas from anyone who has done this procedure on a 1993 300E2.8 before? Am I missing something obvious that will make this easier?