iFixit

With the iPod opening tool, gently lift the brown tab of the headphone ribbon cable connector. The tab will rotate up 90 degrees, releasing the ribbon cable.

Using your fingers, pull out the headphone jack ribbon cable.

The front and back of the iPod should now be completely separated.

Use a small iPod opening tool to release the black hinge holding the hard drive ribbon cable. The tab will rotate up 90 degrees towards the logic board, releasing the ribbon cable.

Use your forefinger to hold the ribbon cable in place; disconnect the drive from the ribbon cable.

Make sure the hard drive rubber side bumpers are attached to the drive being installed. Use the hard drive rubber side bumper installation guide to accomplish this task.

If necessary, the blue foam padding on the hard drive might also need to be transferred to the replacement drive.

Use the small iPod opening tool to release the brown clamp holding the hard drive cable in place. The tab will rotate up 90 degrees towards the display, releasing the ribbon cable.

Slide the orange hard drive ribbon cable directly out of its connector. The cable may be attached to the logic board with some adhesive. If the cable doesn't immediately come free, carefully pull up on the cable to loosen the adhesive.