Thanks for the reply M.B.Doc, I found a good post over at BenzWorld.org showing easy step-by-step instruction on how to replace the regulator with the one for the W140 S420, instead of replacing the whole blower assembly.

The procedure appears simple and anybody with reasonable handy skills sould be able to do it in an hour or so. I'm very familiar with soldering, and am mechanically inclined as weel, so I'm confident I can handle it.

The only question I have, the Bosch regulator for the W140 sells for $211 at the AllPartsExpress site, compared to $318 for the Behr regulator. Is is worth to pay the $90 difference, or are they pretty well equal in quality?

I also saw one sold by DeutschePartsUSA on eBay, "manufactured by Hamburg Technic in Germany, with a 1-yr unlimited miles warranty",for as little as $71 including shipping. Sure smells fishy, but does anybody here have any experience with that manufacturer?