In my Optiplex 390 MT, I have a CD drive and an empty slot right below the CD drive for another 5.25" accessory.  I want to put a 5.25" multicard reader in the available slot.  The CD + available slot are housed in this aluminum enclosure that itself is attached to the computer case.  The problem is that all the screws and openings are exposed from one side of the aluminum enclosure only. The other side is totally unexposed meaning there is no space for the screws and a screwdriver.  I can not figure out how to remove that enclosure so that I can work both sides.  Is there any way to remove the aluminum exposure or is it non-removable?