I recently got an older Cub 154, got it tuned up and it seems to be working pretty good. It needs a clutch and a PTO pulley key and some bits but nothing major.
However, I have one issue that I'm not sure the best path on, the 3 point hitch leaks down quite rapidly, to the tune of full up to full down in ~20 seconds with a back-blade on it.
Assuming the issue had to be in the relief valve or the control valve (older one where they are separate) I got a rebuild kit from Hamilton Bob's with all the O-rings and went through them top to bottom, everything looked good inside.
After re-assembly, same issue at the same speed. There is no external leakage, so it pretty much as to be in the valves.. Hydraulic fluid is topped up and looks good, it lifts and such all without issue.
Based on my analysis of the valve, it looks like there must be fluid leaking by the poppit or plunger (parts 5 and 6 in the diagram), has anyone ever dug this far into one? I have a lathe so maybe will try to turn some new ones, but thats tricky at the needed tolerances.