I agree with Kevin. Try to get a little up and down movement from king pin. The tapered pin is not as hard as the king pin so it may have twisted or indented from the king pin notch. Maybe a little low heat (not cherry red).
Just a hair brain idea if all else fails. At the round end of the tapered pin, grind a flat spot, center punch, drill and tap a hole but stay away from the king pin. It's hardened. Screw in a bolt in the newly threaded hole. I use a homemade bodywork dent puller (slide hammer) that is attached to the head of the bolt. If you don't have one, improvise.
