I felt a little play in my controls the other day. I rocked my bike back and forth with the front brake locked, and felt a little knock, which can only mean my headset was loose. I've got a Chris King thread-less headset with sealed bearings, and honestly the last time I looked into it was 1o years ago. I learned my lesson today that you should check your bearings at least once a year or two, not ten.
The first sign of trouble was the fact that I couldn't even slide the top cap off one the stem was removed. The thing had frozen shut. I went out and bought some WD-40 to loosen things up and hammered away till it became loose. Even then I had to tap it off the steering tube. No harm done, just needed to file away the dents I put into it (steering tube). Afterwards I sanded away any remaining rust spots and uneven surfaces, and proceeded to overhaul the headset bearings.
To my surprise the bearings were still well sealed and had a bit of original grease. I cleaned and repacked it any way. This headset is pretty much bomb-proof. Now I've got a happy headset. I'm beginning to suspect my bottom bracket is in the same dire need of a once over and at least a good spray of WD-40 to deal with possible rust. I just love stuff that I'm able to work on myself.