I dunno man, I just did mine last week with no problem. I just put a little high temp grease on the spindle shaft and the hub slid right on. Maybe you can swap the hub with another one at the parts store.
Hmm I've never done them on a cobra before, just volvos lol. However I would highly recommend you start by cleaning any of the surfaces very good. If it fits into a "hole" so to speak, try scraping the edges of the spindle with a screw driver to grind away the stuck on gunk. Make sure everything is very clean, then try.
Thanks to all, I got it. The problem was the clearance is incredibly tight. you have to walk it on at the beginning by hand, then tap very lightly on the edges. As soon as it on just a little it slides right on. Thought I was going to loose it.