I've got an HP 2755 desktop computer that a customer dropped off. One of the chores he wants me to do is clean the dust out of the case. Unfortunately, it's a Chinese puzzle (no offense to Chinese - you make great puzzles), and unscrewing the obvious thumbscrews does little to release the top (side?) of the case. There are no obvious shipping screws. It appears that others have attempted the same task because there are a lot of screwdriver marks on the case's plastic edges.

This is the business version, not a regular desktop - it's old enough to have Win ME on it. I've poked around a lot at HP's site and can't seem to get anything going. The machine needs to go back today because there really wasn't much wrong with it.

Any help or ideas appreciated.

Never mind. After about two hours of searching, I finally found the answer.
BTW - it's the 2755 HP desktop, not 275. This slow computer takes a while to echo my keystrokes sometimes.

If anyone else has the problem, the "left" side panel has to be removed first, before undoing the thumbscrews and pulling the metal side off. The plastic panel is on the left if you're facing the front of the case, on the right if you're facing the back side. Both side panels come off the same way. First, remove the stabilizer brace from the front bottom of the case. Then pull the center of the side panel away from the case a little bit and push the panel forward. Complete Instructions