Mine did the same thing just before this part broke:
http://catalog.eautopartscatalog.com/mercedesshop/sophio/wizard.jsp?partner=mercedesshop&clientid=catalog.mercedesshop&baseurl=http://catalog.peachparts.com/&cookieid=1MB12FET61N91D13MR&year=1987&make=MB&model=300-SDL-001&category=O&part=Window+Regulator+Kit

Pretty simple fix.

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1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200