JD utility tractors built from '65- late 80's power steering valve housings are designed for steering wheel/shaft to move up/down a little as this up/down movement actuates the 2 control valve bodies inside the housing. I suggest to remove inspection cap on LH side of clutch housing below steering valve & be sure bolt is tight. Another common location for steering slack is worn-out needle brgs from lack of grease on bellcrank in center of frt axle.