How do I pull this screw?
 

I need to get to the blower motor on a W140 ('95 S320). Another user posted a very complete process for how to do this, but I am stuck on one screw (isn't that always the case?).

I have removed the numerous screws holding down the wiper manifold, except for this last one. The screw turns and turn and turns, but it does not seem to be any closer to coming loose. I removed a few others that from the top appear to be identical, and I shouldn't have to spin that screw more than 20 times before I run out of threads. There is no way to get under it that I can see so I am wondering if there is a trick I need to know about.

The offending item is the one noted with an arrow. This is a picture I copied from the other thread, but mine look just like this (view is from the passenger side of the vehicle). It is a screw about three or four inches long and it is the one closest to the windshield.

http://www.uploadgeek.com/uploads456...sentation1.jpg

Got it, finally. Never did manage to get the screw to loosen with a screw driver, so I rotated the head with a pair of vise grips while gently applying upward pressure. About three turns like that and it gave enough that I could remove it with my fingers. Swearing a bit helped.

Now to get a replacement blower regulator and put it all back together.