No need to pull the rear glass. Just lift the outer rubber and insert sealant all around the window. Mine does the same thing but I have not put sealant in there since I replaced the rear window. Even says in the MB Maint CD that it just need to have sealant squirted in there. Need a tube of sealant with a long nozzle with a thin point end on it. Basically get the tube of sealant and cut the nozzle leaving it with a small hole in the end. Not pin hole small but small.

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~Jamie
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2003 Pewter C230K SC C1, C4, C5, C7, heated seats, CD Changer, and 6 Speed. ContiExtremes on the C7's.

1986 190E 2.3 Black, Auto, Mods to come soon.....