Does anybody know what thread these are - the ones on the right-hand side of the cylinders? Mine were still sealing but with corrosion and thread damage. Local hydraulic shop said they were NPT. Bought a couple of replacements but they didn't want to screw in - didn't want to push it and risk damage . Suspect the threads in the jugs are also corroded and need to be cleaned out but reluctant to attack them without knowing for sure they are NPT.