There are front and rear upper stop brackets that can be adjusted. You do need to remove the door liner to get at them. I have not personally done this, the information is from alldatadiy. The adjustment process is complicated, and you should consider getting an alldatadiy subscription or the Mercedes CD if you are going to attempt it.

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Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe