well there are a few ways you can solve this problem, one being to use a prop reemer, to enlarge the hole, or if you dont have a reemer lying around you could use a drill bit, but uou have to be very careful when doing so. since you said that the prop would go onto the treaded part but not the smooth part make sure to only enlarge it a little, were talking 1mm here if that, and a nother thing if you are going to use a drill bit, do it by hand, never use an electric drill aor a drill press!!! The speed at witch an electric drill would turn could damage the composites in the prop.

Tony