Tractor Repair: ih 574 pto weak, broken spring, mcv

Question
i bought this ih 574 and no powersteering,brakes and pto quit,so I bought a used mcv valve.installed it.now everything works but my pto is weak,checked pressure coming out of mcv before the T fitting and it is about 125psi when engaged.I did not install new gaskets when installing the mcv valve but they looked good.could you point me in the right direction.Thanks

Answer
  This could be a tricky one because there alot of variables.  Not sure what happened that caused the problem or if you replaced just the MCV, or the MCV along with the pump.  Also anytime you install used parts, there are some unknowns.  You really don't know if the used MCV had any issues before you got it.  I don't recommend re-using gaskets or o-rings because it may end up costing you more in the end.  There are lots of valve spools in the mcv that can stick or have a broken spring.  If the steering works good and if the remotes have enough pressure, then you can assume the pump and relief valve are good.  Make sure the pto lever linkage is pushing the pto spool down far enough to give full pto engagement.  You may have to pull the pressure regulating spools out and check them for scoring or broken springs.