Here's the low-down: 1990 190E 2.6 with front pwer seats.

The driverside seat has all functions working EXCEPT that it won't reverse! I can go forward but it will stay there. I've been driving with the seat just barely at comfort position (though a pain to get in and out) and moving the seat anymore forward will make it nearly impossible to sit in the seat. I understand it may be a contact issue somewhere in the controls. I've been thinking about one of those cold dust sprays w/ straw nozzle that Office Depot sells or I've read something in the archives about using an electrical spray? But even with a thin nozzle, how does one spray inside the controls? I dunno, it's about time I fix this seat problem.

bump

anyone? seat won't move back, only forward.

Dunno if your switch is the same internally, but here's a how-to on cleaning one of these from a 1985 W126. (I checked on-line and the 190E switch casing sure looks identical though)
You can try shooting the contact cleaner through the opening in the case that you'll see when you pry off the knob for the function that doesn't work. The cleaner has a high alcohol (I think) content, which evaporates very quickly on the metal surfaces it finds. You might buy yourself some time, but eventually, the switch contacts will need R&R.....

Power Seat Switch Cleaning

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1986 560SL
2002 Toyota Camry
1993 Lexus

The internal contacts are dirty. You can spray contact cleaner into it after removing the knobs (they pull or pry off -- watch that you don't lose the headrest one) and the face plate on the door (I think it just pries off). Flood the inside with spray contact cleaner (safe for plastics, please!) and work the switch and it should be good to go.

If not, take the switch out of the door, unplug everything, remove the screw in the back, pry up the clips that hold the front on, and VERY CAREFULLY lift the front off from the back of the switch with the front facing up. It's full of tiny bits, you don't want them to go jumping off the table, believe me!.

Inside there are about six pairs of rockers with a pair of ball bearings top and bottom with a spring in between. These rockers have pivots that fit into slots, and when rocked over press a wing-shaped contact onto a stationary one. You can either gently spray them down until they are all clean (center contact and the one on each end, plus the stationary ones) or clean them with a new pencil eraser. Put it all back together, making sure there is a ball bearing on top and bottom of each spring, slip the front back on and press down to clip the clips back on, then install the screw. Should work fine then. Gently shake before re-installing -- if there are loose bits rattling around, take it apart again and get it all sorted and re-assemble.

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!

Thanks, guys! Oh, those control "buttons" pull off? Do they pull off straight or at an angle? And how do you pry the plate off? Which side, one closest to the vent or the one next to the door handle? Thanks again!

Grrrr, I can't seem to pull the buttons off (the forward/backward one)! I'm afraid to continue. Are they supposed to just pull or slide off? Don't want to break anything.

pull straight out. then remove circular set ring behind largest tube that sticks out, and then take plate offf