Okay, this project is officially bugging me.
I put some shiny new balls in the front hub, and although at first it felt like it was going to be smoother I ran into the same problem. The bearing feels a little but tight/noisy when I spin the wheel, but when I grab the rim there's still a little knocking in it. Like 1-2 mm movement, gauged at the fork/brake area.
Any further ideas???