Thanks for the replies. I think I found the problem.

The filters showed signs of rust. For several months now the fuel gauge has been unsteady at times, and it moved with the sloshing of the tank. I put off pulling the tank sender.

Yesterday the gauge would only read full left or right, nothing between, and oscillated as the car moved. I removed the sender, or what I could get out. The nut holding it together had come off, so that nut was lost in the tank, along with the bottom large washer, and the plastic "maze" that slowly drains fuel from the sender. I did get the metal cylinder and rest of the sender out, but the wires were broken.

My guess is, this stirred up the junk in the bottom of the tank. I'll watch the filters, and carry my wrench from now on. And I think I'll go with a 20K filter change interval from now on.

Ron

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1971 220D, daily driver, new paint, 142K
1973 220D, low compression
1975 300D, back on the road! 166K
1971 220D, salvage, rear hit, engine excellent
1972 250, bad cam, but runs!
1971 230, engine stuck
1971 220D, low compression, rusty
1976 240D, salvage, engine excellent
1966 230SL, water in oil after rebuild