Battery completely dead. Screen was damaged 2 years ago (black streaks across), so I decided to fix both at the same time, since the parts were very reasonable in price.
Went very well. Separating the two halves of the outer casing was the hardest part. I wouldn't want to try what it takes to seaparate the iPod Classic's all metal case. (I have taken many Mac laptops apart using iFixit's wonderful guides, so I have the tools and lots of practice with tiny connectors.)
Go for it. Why waste a perfectly good (after the fix) 30 GB iPod Video? Now we have two of them, so we're going to sell or give away the 2nd (my wife uses iPhone instead now).