Hydro leak

[Farmall 504]

504 has had the usual slow hydro leak under right side seat. Tolerable. But the pipe running along the bottom of the base of seat front, then up and connects with a big nut going into the block at side, has sprung a leak right at that nut. I've not done much hydro work, but it seems there would just be a simple seal behind that nut? And the pipe moves just enough that you can get behind it to install?

Any info/advise to repair much appreciated.

Been through my shop manual, can't seem to find this. 20 pages on power steering, but can't find a diagram or words on pump plumbing.

 

[BarnyardEngineering]

It's probably an O-ring.

Parts manuals are available online at the CaseIH website.

 

[used red MN]

I suspect the assembly you are concerned with is in the 1st or 2nd section from the top in the linked page. On a phone to view the parts diagram once you select a section you need to select the picture icon at the bottom of the page.
CNHI Farmall hydraulics