iveco daily brakes?

Hi all, is there any way i can test a load sensing valve? i have it removed from vehicle and poured fluid in, when pulling the pips with pliers, one side the fluid moves from front hole to back hole, other side the fluid moves to front hole then dissapears. this is an expensive part that i replaced 2 years ago and i'm looking for a cheap fix, any idea's?
(2001 iveco 35 s 11)