Working on a Clark model - CGP25. s/n- P365L-0007-9489FB. has the 2 port brake valve, does anyone have ant tech data on how the pressure side of brake valve is suppose to work. somebody has worked on this unit before me for sure. the line that feeds the valve comes off the return side of the steer orbitrol and tees back to the tank. therefore there will never be any pressure there,just flow back to tank. any ideas ?