Possibly someone got a litle too agressive on steering box adjustment? Partially seized tie rod end or ball joint possible as well. You may have to divide up system a little to find it. The steering box may have an internal bind that is other than adjustment as well. Idle arm jammed up a little or perhaps an unnoticed bend somewhere may be a factor. Would lift front wheels off ground and have a friend help checking things. Anything unnaturaly tight might be observable or felt. Could even be something like a bent or abnormal drag in the steering damper as well.