i had the same problem with my 96e320. the right rear window was making grinding sound when i try to make it go up / down. window does not move. but i can push it up and down manually. I followed some of the instructions from this site and got it fix today. Parts you will need are one heavy duty rivet tool, got mine from harbor tool frieght ($13 on sale), one window regulator, 4 rivets, and a drill. Just do a search on this site "window regulator", u will find all the information you need.

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96 E320