X'2 on putting it on backwards. Had the same issue with my new one not going on easily.
Put it on backwards until it lines up. You should be able to get it to slide up onto the shaft. Once its on, it will be a little tough to get back off. The way the prop is fit, wont let you use the puller without using a deep well socket to add some space between the end of the shaft and the threaded point on the puller.
I used this method a few times putting it on and off. Went on in the correct direction very easily after.