I've got a stronglight headset that now has some play when the front brake is applied, and I rock the bike back and forth. I know it needs tightening, but I don't want to screw it up.. I would just take it to the lbs tommorow, but alas...its closed, and I really want to ride it.
(锕侊箒)~~~~----------------------------------------------------------------------
In general, threadless headsets are easy to adjust. See for detailed instructions:
1. Loosen (horizontal) pinch bolts that clamps the stem around the steer tube
2. Tighten (vertical) adjusting bolt on top of stem. This "preloads" the headset by essentially compressing the system. Tighten enough to remove play, but not bind
3. Tighten (horizontal) pinch bolts.
4. Done - go ride.
(锕侊箒)~~~~----------------------------------------------------------------------
^^^ What he said.
The only "trick" is that the pinch bolts allow you to make the adjustment with the vertical bolt, so they should be loosened, the vertical bolt adjusted, and then retightened. Sometimes people incorrectly just try to tighten the vertical bolt.