I got a "new" switch for my Mother's W124 wagon to replace the one I broke a couple months ago attempting to clean it with contact cleaner and "cycling". The lever for the seat back tilt snapped off.

When I got the swithc (used, off eBay), I discovered that it was not the same as mine, missing the memory buttons. While I can live without the seat memory, it's nice and the controller is still there, so I decided to try to take the switch apart and clean it.

Took the screw out of the back, pried the little clips away from the shell, turned it over, and dumped a billion little bits on the table. Oops, I wanted to see how all this fit together, eh?

Turns out to be fairly simple. There are four "rocker" switches that are identical, and one small one for the headrest. That one is easy, it's just a plastic part with a spring and a ball bearing, with the bearing acting as the switch element. The others are a bit more complex.

Each contains a pair of spring holders, in the bottom of which is a ball bearing. The bearing runs on a little wing shaped bit of brass with a contact on each end that mates up with another contact on the brass condutors on the bottom of the switch body. They all ride on brass tubes that allow them to swivel, and they are all loose once the top of the switch is off except the one for front/rear seat movement. That one is wedged in, and I didn't try to remove it.

Once I had the bits all sorted, I took a look at the contact points, and discovered that they all were covered with gunk. I believe they are platinum plated, at least they are silver colored when clean. I just cleaned them off with a pencil eraser, they came bright silvery in a jiffy. The "wings" for the fore and aft switch come out from under the toggle easily from the side.

Had to take the other switch apart to find out where the "extra" set of ball bearings went -- turns out they sit on top of the springs in the toggles -- and to retrieve the toggle for the seat back. Laid all the bits back in and very carefully set the top on and clipped it down. No rattly bits, so I installed it in the car and it works like new.

If you cannot cure a balky seat switch with contact cleaner (it's difficult to get it where it will do any good), it's worth the half hour to take the switch apart and clean the contacts by hand. Leave it plug side down when prying off the front so you don't scramble the innards and maybe loose one of the ball bearings, and check for loose bits before plugging it in, should be fine.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!