I bought my roadbike a few months back and the bearings in the stock shimano 600 headset were toast. The fork also shuddered and make a clicking sort of noise under braking. I just replaced the headset with a new Dura Ace (1" threaded). Its buttery smooth but the fork shudder is still there.

I haven't toed in my brake pads which I know could cause this. They don't seem to be able to be adjusted left to right, only up and down in the caliper. When I hold the front brake and rock the bike forward and backwards, I can literally see the fork blades bend back and forth. I'm wondering if this fork is shot? Its a kinesis aluminum.