I have machine with 3500 psi and 8gpm with gp fixed 3-5gpm injector..my problem is it was working fine but all sudden injector stop working after or during one job. I have checked the spike before injector and its 400psi but checked it right before the gun and its about 1000psi of pike..not sure if that's norm.,any that can give me tips on what to check? Thanks