After messing around with it, I answered my own question. The bottom cap pops off. I used my fingernail to make a gap in the seam, and inserted a small screwdriver to pry it out. The sides then popped off, exposing four small screws on the back. I took them out, and the drive came out easily. I placed the new one back in, reinstalled screws, sides, and bottom, and it works fine!
Rich, January 2008