John Deere 4555 hyd 3 point hitch will not go up or down

SOURCE: Three point hitch on 2020 Jogn Deere Tractor will not raise.

IF the rest of the hydraulic system has normal pressure, then the control valve for the 3 point may be faulty, or ; the hydraulic cylinder that raises/lowers the 3 point arms has failed (the sealing ring on the internal ring has torn)

SOURCE: hydraulic problem

Check your hydro preasures,pump could be going out,also could be in your relieve valve which will be cheaper,hope that is your problem because of the cost,Sound like you know alot about it, and trust you have a high mechancal ability,I have a hunch it could be in you valve, hope this helps,

SOURCE: Manual needed for JD 3 bottom plow w 3 point hitch

The first thing to do is get all the information you can off your plow. Like: serial number, model number and any info on any tags you find then go to the John Deere web site. Go to the plows section and you should find everything you need. They do have parts lists and manuals on the site. But it may be harder to find parts without at least a model. But they do have help areas you can try. Try there and if no luck try to give me all the info you can about what you are looking for and I'll do some research for you.

SOURCE: my 345 john deere hyd pump is whining

What does your fluid look like is it milky?also you can be getting air in the system,And the most important the hyd filter change,and your pump just might be getting tired