D5m xl. No Hyd response?

Replaced Hyd pump few months ago. Worked decent up till lately. Had been getting slower an slower with Hyd functions, sometimes have to wiggle joystick everyway possibly to get blade to move. An today it just pooped out all together, Have already pulled control valve out prior to this few months ago An went threw it an replaced resolver seals on primary An secondary both an replaced balls too, my machine is equipped with a fourth control valve for a auxiliary control, I have hooked gauges into signal pressure test port an read around 450 area. Also read 450 area for the pump stand by pressure as well. Just seems like there’s something leaking internally an not letting the signal pressure tell the Hyd pump to upstroke. Serial number prefix is 4BR