_David Diamond wrote me pointing out that the 5900s from 2000-2003 had a problem where the headset was not loctited down so they are sticky. Its a little complicated to fix, but he has the procedure. Trek will fix under warranty too apparently. Here are his fix-it notes or maybe take it to your local bike shop and print this out since I’m sure they won’t have heard of this problem_
Best to use a workstand for this operation. Obviously you have the fork out of the headtube. Clean the inside of the lower cup with acetone. Careful not to get any on finished surfaces (it will remove paint, etc.). Clean the outer surface of the lower bearing also. The outer surface meaning the flat metal area that is parallel to the headtube and steerer. Place Loctite 680 on the outer bearing surface and the same area inside the lower cup the Loctite on the bearing will come in contact with. Just apply to a Q-tip so you can get it just where you want it.
Carefully insert the fork up into the headtube and make sure it is seated all the way in. You have about 10 minutes to assemble the top
headset/compression ring and stem. Adjust it real snug at first to make sue that you’re completely seated and the bottom and top bearings are parallel.
Now back off the adjustment a little so that you can smoothly turn the handlebars all the way to the left and right without any areas of
Don’t touch the bike for 24 hours as this is how long it takes the Loctite to completely cure. You should be good to go at this point.
Let me know how this works for you.