You don't say whether the windows on the side you're referring to actually operate, and if your question is simply related to how those switches feel when pressed, or whether the windows don't operate at all with the offending switches. I have never looked on the inside of those switches, so don't know if they are designed to "click" when pressed in the up or down positions. It seems to me that in mine, some do and some don't, altho I have only OE switches installed. Nevertheless, the windows operate just fine either way. I do know, however, that when my driver's side front window switch eventually got "mushy" and sloppy feeling, it was broken, because it no longer activated the window motor. Frankly, if I had my druthers, I'd like the switches not to click, but to have a nice smooth rocking motion up and down.

As for replacement, that's about the easiest DIY job on your car. The console wood trim removes readily by removing a single screw under the mat in the console tray (at least on the E class), and the switches pull straight up off their electrical connectors. Press the replacement switch onto the electrical connector, re-fit the wood trim around the shifter and re-tighten the screw. Total elapsed time: 2 minutes.

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1988 California version 260E (W124)
Anthracite Grey/Palomino
Owned since new and still going strong and smooth
MBCA member

Past Mercedes-Benz:
1986 190E Baby Benz
1967 230 Inherited from mom when she downsized
1959 220S Introduced me to the joys of keepin' 'em goin'

There are only 10 kinds of people in the world--those who understand binary and those who don't