While the click wheel is definitely the first part to replace, Apple made it very difficult to do so on these iPods. The click wheel is sandwiched between the front panel and a metal plate that is glued onto the front panel. If you are replacing just the click wheel, you will need some intense adhesive to make sure the metal plate adheres to the front panel. Otherwise, pushing the buttons results in the whole click wheel recessing into the iPod (we've seen this happen with this repair attempt).
Otherwise, replace the front panel with one that includes the click wheel!