I just serviced my headset (on my '99 Schwinn Moab) last night for the first time ever. Never done it before. It has cartridge bearings in the headset. I carefully pried the seals off to get to the balls. The bearings were in good shape, but lacking, IMO, sufficient grease. I disassembled everthing, cleaned/degreased all parts. Repacked the bearings. Reassembled everything. Only had one mishap: I "opened" up one of the bearings too much and all the balls fell out. It was quite difficult to get them back in, but I did it.

I was nervous initially, not having experience doing this, but glad I risked it. One more thing I can take care of myself.