I rebuilt mine as well with new O rings that were close to same size & seem to be working. auxiliary valve I thought was not letting oil return so I took apart & ended up breaking the back of valve where it hold the detent spring & balls. had to have a new one machined & left the detent out. I built a quick attach plate for my JD 54" snow blade, but when I tried to turn blade, hydraulics would only let it go one way. I was sure something was wrong with valve. Long story, but nothing wrong with valve, it was my pioneer connections. One was not letting oil return. Simple fix, but guess i got educated on the 3 spool valve. The blade works great by the way. Next project planned is building my pallet forks with removable grapple. Will show some photos when i can get them downloaded to computer.