I'll try this one more time then let it die. I don't have any other cassette to try, but this is the second one that has had the same result. If you look straight down over the cassette between the large cog and the spokes, you can clearly see some of the hub grooves on one side while the other side is snug. It's almost as if something is keeping the cassette from completely seating on one side. However, when I've examined the free hub, there doesn't seem to be anything that would cause this. I thought about trying to slide on a spacer first, then the cassette to see if that would force the cassette become flush with the freehub. Although, it seems like that may cause some other complications.