A friend recently gave me her broken 4th generation iPod, 20 gigs, which had a broken screen and would not start up. After some searching I found a $48 screen on eBay to replace the broken one, but now I had a problem; I love the look of the 3rd gen, on the left, but my iPod had only 10 gigs and was full. I needed the extra HD space.
To open up the iPods, I used a guitar pick to go around the edges and pop up the six clips. The hard drives are held in place by a piece of tape, I removed that, then removed the HD. Switching the HDs is easy, but the different generations use a different filesystem, which requires using either the ‘restore’ button in the ipod updater, or ‘erase’ in Mac X’s disc utility. Both hard drives run like new. As for the screen, five screws are required to be removed to get to the broken screen. Pulling it out is easy, replacing it with a new one is close to impossible. Two hours of careful pushing put the new screen in it’s place, working perfectly.