If you're not comfortable with giving it a big YANK then use a dremel
tool to carve up the side so the phenolic will lose its grip. Careful
dont go too far and hack up the shaft.

-SP

The rotor sometimes acts like it simply won't come off.  It's critical
to exert only axial (i.e. parallel to the distributor shaft) force to
get it off.  It's real easy as you rock it to try to get it off to end
up putting some radial force on it which will cause it to jam.  Keep
trying, being conscious to exert axial force and don't be afraid to put
some force on it.  You can't break the distributor shaft by hand.  I've
often thought that a dab of white lithium grease on the rotor sliding
surface might be a good idea but I've not tried it.  Good luck.  Al