Yeah I also have had a few take a dump on me. I had a 60MB one originally in mine and last week when I was putting it back together the HD would knock and did not work. Worked fine before. No big deal as I installed a 4.86GB Travelstar in it, and cannot be happier.
Bottom line people, if the HD in your new Amiga is the only thing that doesn't work consider yourself blessed and just replace it!!! Don't even make a fuss to the seller.