Originally Posted by
HillRider
I expect the bike was in a front end collision of some sort early in it's life that bent the steerer tube. From then on the headet would never adjust properly.
That's my current best guess, too. It's kinda weird that the steerer tube would bend 1/4 of the way up from the crown race, instead of at the joint of steerer tube and crown (which is more typical).
In addition to the asymmetrical bearing forces as a result of the bent steerer tube, the threads above the "drawn" section aren't perfectly parallel to those below. But that second asymmetry is consistent with the tube being drawn thinner on the backside (where the hole is).