I have been working on a H4.00DX with a brake problem, the brake problem being that it has torn the linnings off the shoes four times the last time only taking 57 working hrs to do the damage.The last time the shoes were relined they were also riveted & they still failed! Have i got a hydraulic boost problem can anyone sugest what may be causing the problem ? Hydraulic line pressure to the booster/master is 1100 psi.