The window channel is a square section insert -- metal back, rubber or rubberized fabric sides, covered in a felt like material. If the sides have separated from the back, or the back has broken at the corner, the window will cause the center section to lift away from the rest of the channel, and give you a slot.

I cannot believe the door has actually split, MB window frames are pretty tough.

What part is moving when you close the window all the way -- the black "stuff" that the window rides in?

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!