I just laid out there under it staring up at it trying out Professor Harold Hill's Think Method, thinking I could maybe just 'will' it into jumping out of the hole. Didn't work. (It worked on the Music Man, dang it!) I'll let you know how it goes tomorrow.
LOL I've wished a couple times that Magic would work for me too. But usually good ol determination finally wins the day.
I haven't had much success with a slide hammer, and once you have drilled and tapped a hole for a pull bolt, you might as well drill out enough of the lock pin that you could drive the kingpin by the remnants. The trouble with that is keeping your drill straight so you don't hog out the hole the ping goes into. I really think that the hydraulic jack push method would work. I think you could fab up a frame with a pin on it and get that bugger out of there. I think that removing the brake backing plate would give you enough room to do something similar with the kingpin. That might be less involved than removing the whole axle.
[on edit] I like buoymaker's idea of welding something on to the lock pin. If you can get close enough to keep from welding it to the axle, a bolt would give you something to pry against (prybar behind the head).
