I recently had one of the 2nd stage piston seals go out. Replaced it & now it will build pressure to around 3500psi then start loosing pressure. Can’t find a leak when it running. But it also sound like it’s in a bind starting around 3300psi, then at 3500psi it stars loosing pressure. Any ideas on what to look for?? Gonna tear it back some later this evening & see if I can see any thing.