I believe all the door surround rubber is held in by friction, that is, no gluing.

Whatever you do, get genuine MB parts for these. Aftermarket "rubber" has too much "carbon black" and not enough rubber, so they deteriorate faster.

Here's a tip if you have access to a smoke-machine:

1) close all doors and windows; start the car, and turn-on the fan to HIGH to pressurize the cabin;

2) using the smoke-machine, preferably inside a shop with no breezes, pass the smoke around the suspected seals (or all seals) and see where the smoke is PUSHED away by the pressurized cabin.

:-) neil

PS: get the factory manual and/or CD-ROM and it will show you how to replace the door rubber seals.