I'd bet it's the clips. There are two per front window and one per rear window. There are only about four screws that hold the door panel on, the rest are clips. You can get new door panel clips from eBay for cheap. Get the window clips from the dealer. I'd also suggest getting interior trim removal tools so you don't ruin any trim pieces. The tools are usually less than $15 and make a worlds difference. This is a very easy repair.

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03 3.0i mt
89 325is