Howdy Don,

Apparently that is a factory adjustment:

The adjustment screw (1, Fig. 63) is provided for adjusting manufacturing variations. The first made and carefully checked adjustment is normally enough for the whole lifetime of the valve. The adjustment screw should therefore normally never be touched.

However, an adjustment can be done if it has been satisfactorily established that the outgoing pressure is outside the normal variations, according to "Service Diagnosis, step 9, Group 50. Turning clockwise increases the outgoing pressure. Lock the screw carefully after turning, lock nut torque 2.-3.5 kpm = 18-25 lb.ft. Adjustment is allowed only after overhaul.