You don't beat on the head of the screws.... You lightly tap the valve body, it slides maybe 1/8" total but if it moves to either end of it's travel the wheeling wheel will be spinning till it hits the end of it's travel...
Look at the machined groove in the steering box picture below, the valve can only move within the groove....
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Don't worry about the red arrow, pay attention to the groove, the valve slides in that groove... tap either end of the valve with the engine running & you'll see the effect... The tires should be off the ground... When you get it so it doesn't turn to either direction with the wheels in the air you are close... Shut the engine off & watch the steering wheel as you start the engine.... The wheel shouldn't move at all, if it briefly kicks to either side your adjustment needs further tweaking... If it doesn't move tighten the bolts & top off the fluid....
In the service manual they mention tapping on the bolts... What they are referring to are the bolt and cap with the red arrows in the photo below...
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