Hi all; sorry for the horribly late update. I reached the Novakon support guys and it took them all of 20 seconds to diagnose the problem by hearing it over the phone. The front block that holds the bearing for the Y-axis ball screw was gummed up. It was packed with grease and jammed up a bit. I just had to clean it out with some penetrating lube and then hit it with some good grease. The problem vanished instantly! Thanks all for the good advice everyone! I certainly know the mechanics of my mill more now than before!

-Mike