I just did this last night. The D5100 tear-down guide above was a big help. You need a tiny phillips screwdriver (like for repairing eyeglasses) and tweezers for handling all the tiny screws. A sharp pick tool is a help as well. *EDIT* Here is the complete guide WITH PICTURES: Replacing the Nikon D5100 or D3100 SD Memory Card Door FIRST: open the memory card door and take a good long look at how the spring is installed. There are two "feet" coming off of the spring that need to be installed into two "insets" on the rear camera cover, this has to be done before you put the cover back on. 1. Remove 3 long screws behind the eye-piece (note that the one on the top-left is slightly longer than the rest and uses a different thread), then remove the plastic cover over the diopter (a pick tool is helpful here) and remove the silver screw behind it. (4 screws total) 2. Peel the rubber thumb-grip back slightly, there's a short screw there closest to the left side of the thumb-grip. This one seems to be slightly thicker...