Are the 2 revolutions smooth before it stops ? Greased threads ?
Did you try "forcing" it by hand ? Get a good grip by hand and give an extra oomph. Maybe just a burr in the frame.
I assume you're turning the right direction, counter clockwise to install, otherwise I doubt you'd get 2 revolutions.
Last edited by Homebrew01; 11-06-15 at 07:26 PM.