Would still like to see a picture of the head angle when the aircraft is loaded and level on the ground. The tension on the kingpin has nothing to do with how the tail wheel breaks. Just how much pressure it takes to move the tailwheel. I also don't leave any slop in the tail wheel bearings. I apply a bit of drag.

I would like to see how much slop there is between your fork and the steering arm and post some pictures. When it won't break over easily it is usually slop between the head and the steering arm or the groves are worn where the arm locks.