Originally Posted by Jeremy5848

I've not had the problem you are experiencing. Mercedes generally makes (or subcontracts) parts that can be disassembled and this switch is no exception. If you will remove one switch from the car and examine the base (where the wires clip on) you will see two tabs that hold the guts to the body. These can be pried apart to take the switch apart. The metal components can then be cleaned. Note that they are silver-plated and should be cleaned with a metal polish and a q-tip rather than steel wool or sandpaper. I use Mother's Mag and Chrome Wheel Polish only because I have it around for car stuff. You can also use household silver polish.

New switches are available. Click the "Buy Parts" link at the top of the page and patronize the good folks who support this web site.

Not only can you buy new switches, you can get the new design in which the plunger can be pulled out into a locking position. This allows you to have the door open with the key in the ignition (while you are doing some kind of test on the car, for example) without having to listen to the buzzer.

Edit: As MBeige notes in the next post, the new switches have a gray plunger while the original ones (non-locking) have a black plunger. They occasionally turn up in junkyards, especially as trunk light switches.

Jeremy