the power steering on my 77 has all new parts and peices,but steering wheel does not turn like it is a p. steering car.The wheel does not return after a turn with smoothness of a p. steering car.I backed out,1/4 turn,the slotted screw adjuster on top of steering box,then another 1/4 turn,but wheel does not turn easy enough.Did I read somewhere  the that control valve has to be bled? Could it be airbound?