Gerard,
There is and exploded view of the pump on the website under "Hydraulics".  I can't find the original jpg to send along at the moment.
Parts #29 are the adjusting screws.  The left one is the high pressure relief valve (small ball, approx. 600 psi/turn).  The right one is the low pressure relief valve (large ball, approx. 350 psi/turn).
To adjust, loosen jam nut, turn adjusting screw cw to raise pressure ccw to lower pressure.  
To check the relief valve setting force the pump to stay on (jumper across the pressure switch) and measure the pressure in the system.  Err on the  low side when making changes as the pump can put out 3000 psi.
Chris Zavatson
N91CZ
360 std