You definitely need a new vacuum pump for the self-closing doors. Best price is with Phil at MercedesShop.com, although be sure to provide him your chassis number, because there are four different types of vacuum pumps for this same feature.

Replace all missing switches and see if the seat works.

I hope the suspension noise is not related to the self-levelling device on the rear axle, because it could be expensive $$$. Have the system checked by a qualified technician.

I believe there is no way to activate old W140 phones anymore, although check with your local M-B dealer to see if someone provides the service for your phone type.

About the transmission, I would start by changing the fluid and installing a new filter. Then see what happens...

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]