I've had the same problem. ALL of my windows are scratched badly because of the grit getting in the rubbers. I assume you're talking about the rubber that runs along the bottom of the window glass (outside) where it disappears into the door cavity?

I took mine out and cleaned them with soap and a scrubbing brush... helped stop more scratches, but the grit came back after some time, so back to square 1.

How much were you quoted for new ones?

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1988 300CE 124.050 M103.983
1986 190E 201.024 M102.962