504 Farmall - seized rear hydraulic pump

I bought a Farmall 504 gas this winter. An old farmer helped me go through it top to bottom, except for the rear hydraulics, which he did not have time to help me with.

3-way hydraulics for the tractor"s Farmhand loader bucket/grapple work great. We completely drained all tractor fluids and added new, checked hoses and connections, etc.

The lever on the rear hydraulic pump by the seat barely budges, though, and appears to be rusted/seized even after lots of PB Blaster. I can barely move the level/cylinder even tapping with a hammer. It will move 1-2" only. I opened the rear hydraulic faceplate to see what was inside. One of the three holes has hydaulic fluid in it, but nothing gushed/flowed out. Maybe one or two drips. Other two holes seemed dry.

What would my next steps be to try and fix this problem?

I"d like the rear hydraulics to work to raise/lower my old NH sickle mower when cutting hay/pastures. I don"t need hydraulics for my old NH rake or square baler, so if you have other suggestions for pulling the mower up over rocks/gopher mounds, I"d appreciate that, too.

Thanks first of all for correcting what I"m calling things - after my husband left a year ago, I"ve been trying to learn everything on my own (he never wanted to teach me mechanical things):) I have an old 504 manual I bought on Ebay coming, but it has yet to arrive . . .

I believe you"re right on the rusted valve. I"ve removed the cotter pin and part of the lever, still PB Blasting the remaining part.

I"ll let you know what I find in a couple of days when I find a little more time to work on it.

Thanks so much!

When I do find a solution/get more info I"ll let you know. Your front/back hydraulic valve shutoff would make sense. I did just find an old user"s manual online, too, that should arrive next week. Hopefully that will help :)