The driver's side front door on my 83 380 sel is missing the upper back portion of the rubber window channel (the part the glass slides in). I found a perfect replacement for it at the bone-yard but before I try to pull it out, can anyone tell me if it is REALLY possible to remove and/or replace this part without removing the window glass?

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2000 Mercedes S500
1990 Mercedes 560SEL
1970 Triumph Spitfire