Most seventies bikes had threaded headsets and quill stems, so this is a generic procedure that should work unless the quill stem wedge is stuck in the steerer tube because of corrosion, in which case check out Sheldon Brown's article on stuck stems
HERE.
1) Remove the quill stem from the fork steerer tube by loosening the expander bolt and pulling the stem up and out of the steerer tube.
2) Remove the fork cone lock nut from the threaded steerer tube.
3) Remove the washer and adjustable cup.
4) Carefully remove the loose ball bearings trying not to lose any (or ball retainer with balls).
5) Carefully lower the fork from the bottom of the head tube, again trying not to lose any loose ball bearings.
