Originally Posted by habilis

If your headset does NOT have a large lock nut at the top with flats for a big wrench, I don't see how it could be cup-and-cone (loose ball bearings). The nut is needed for locking the cones in place after adjustment.

If you have the big nut right where the handle bar stem begins, place a large box lid under the bike to catch any loose balls that may fall out. Loosen the nut and push it up the stem and out of the way (maybe hold it up with tape). Lift the upper cup and inspect the balls. This will at least tell you the condition of the upper bearing. If there's enough grease and the bearing has been turning smoothly, maybe leave well enough alone for now. In any case, you've worked on this type of bearing and will know what to do.