The regulator guide jaw, is less than $6 from Phastlane Phil (see parts link above)http://catalog.peachparts.com/RenderScriptTemplate.epc?_cmd=epccat_VehicleAAA&cookieID=2G212TH442G31C5HNS&yearid=1992%40%401992&makeid=MB%40%40MB%40%40X&modelid=300%2DE%2D002%40%40300E&catid=O%40%40Body+Mechanical+%26+Trim&mode=PA&subcatid=O3035@@Regulator+Guide+Jaw&source=www.peachparts.com&clientid=catalog.mercedesshop
I have replaced one on a 126 body, but not on a 124 - your's looks like it might be a simpler procedure.
Unless the regulator is bent, or a gear is stripped, there is nothing wrong with it, and it should not need replacing (just replace the jaw, and save $$).

Good Luck!

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It is a truism that almost any sect, cult, or religion will legislate its creed into law if it acquires the political power to do so. Robert A. Heinlein


09 Jetta TDI
1985 300D