Originally Posted by
rothenfield1
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.
Pics.
Otherwise, all I can believe is that you failed in your examination.
If your freehub body is ally, but has normal-depth splines, there's a chance the cassette is getting hooked up on damage from previous use (normal HG splines are too shallow for ally; the cogs dig in).
Using a single cog, find out why you can't slide it all the way home on the splines.