SL/R129: Beckwithr
I need more information about your vehicle to supply an answer to your questions.
I discovered I have no documentation on the multicontour seat. If this were an R230 car I would check the pneumatic supply from the PSE pump in the trunk. Specifically, I would apply vacuum to the line connected to port "MKL" using a hand-held pump that can be borrowed or purchased from Autozone, and I would see if there was a leak. Your R129 may be the same in that it has a dedicated line for the seats marked "MKL".
You may have to have it rebuilt if bad as one of the pumps in the R129s (p/n 129 800 2048) is NLA...it is the one with 7 nipples , one of them controls the seat functions.


