Originally Posted by
kmcrawford111
Only the top locknut has wrench flats. The top "cup" - the part that goes just above the ball bearings - has a knurled surface instead. I suppose I'm supposed to hold that with "Channel-Lock" pliers while turning the locknut with the headset wrench, ya?
You may end up doing that, but it might not be the original intention. Some forks have a groove cut across the threads, and then a washer with an internal tab. The washer goes between cup and locknut, the tab keeps the washer from rotating, which isolates the the cup from the locknut movement, making it possible to torque the locknut with only one tool.
Originally Posted by
kmcrawford111
This is a lot like overhauling wheel axle hubs, isn't it?
Yes indeed. The basic concept can be found in other places on the bike too, pedals and BB for instance.