'83 JD 500C backhoe. I had asked this a while back & thought maybe they'd loosen up from use, but little to no improvement. The 4 control levers for the backhoe part are all stiff. The 2 outer ones to raise/lower the stabilizers are stiff, but workable. The left one does tend to want to stick instead of returning to a neutral position when I let go of it when pulling back to raise. The 2 center levers for the arm & bucket are much stiffer. The left one is especially bad for swinging the arm left/right. Very difficult to move so I end up pushing a lot harder than 'normal' and then get a fast swing. Making a nice easy left/right movement is nearly impossible (but it's smooth enough moving forward/back and can make fine movements). I can either bump it and let the arm 'creep' or else it's going at full speed. Anything in between is hard to get the right spot. This lever also seems to dislike being in a neutral center position. Just driving around will often let the lever bump a little and the arm slowly swings itself all the way to one side or the other. By slowly, I mean it will go from centered to bumping up against a stabilizer over 5-10 min. Sometimes it stays put, sometimes it drifts to either side - probably determined by how rough/bumpy the ride is. The right lever seemed to loosen up a little with use. Still much stiffer than a typical control, but I can make fine movements, it returns to center, & doesn't drift. So far, I've found about 2400 zerk fitting to grease the machine (I might be exagerrating by a few), but i don't see anything around these to lubricate. Haven't taken the cover off & really looked at it - mostly because I don't know what I'm looking for. I assume there's some sort of cam or springs that make the levers want to return to the neutral centered position when you let go of them? I could look for something like that or crud in the area. Maybe spray the linkages with some penetrating oil & work them around? I haven't seen anything in the OM about maintenance for those controls. Since I know little about caring for this machine (I've always rented & let Hertz worry about that sort of stuff ) I don't know if there's some basic maintenance task that would fix me right up or if this is an indication of a serious problem with that cluster of hydraulic valves or a hydraulic return issue or some other 'needs a shop to fix' sort of thing. It does dig just fine. Have done a lot of work with it. It's useable as it is, just annoying always checking & correcting the swing position when I'm using it as a FEL and finessing the swing position to get it just right while digging.
For safety it is worth getting it fixed right take that back cover off see what is going on with the linkage, could be a torn Oring/broken springs in the valve, they are not hard to replace. Good luck
I don't know anything about your machine or the controls but I will ask you to look under the control block for caps that may be screwed to the control section. Your linkage is fastened to the top end of the control spools. At the bottom end, I'm thinking you should have a cap (may look like a small pail) that houses the spring and spaces. Those caps are not in the oil section and can be removed without loosing any oil. They can be full of rust and causing the spring and spacers to bind. Have a look.
not sure about your machine but i know the older cases 580d-580k suggested a HTO additive that prevented moisture in the hydraulic oil and deposit build up around valve spools due to the lack of additive in the older tch or cheaper tractor supply hydraulic oils i have come across it change the hydraulic oil and filter and try a hydraulic oil additive...also the clevis pins in the control linkage could be rusted pb blaster or better yet take them out and replace them with new pins and add anti seize to the new clevis pins or can you see if the control valve is leaking externaly?
Messed with it a little today. Sprayed penetrating oil all around & worked the controls. They all feel normal now except the swing control. The red star in the pic. Still very stiff, but felt like there was about a 25% improvement. Did a little digging & it was easier to get the swing speed I wanted without jerking the arm. So everything now feels about 'normal' except that one control. And it continued it's behavior of slowly moving the arm to one side while I was moving about 20 yds of dirt from one place to another. The best way I can describe moving the control stick left-right to swing the arm is it feels like it's binding. Should I pull that little black boot out & get some oil inside it? This is the exploded view of the valve from the parts manual. No idea if the problem is in there or in the linkages or somewhere else. I don't see the cap Deon is describing but a JD might be different.
#1 is the cap on the bottom of the spool. Never hurts to be real careful when removing in case something wants to shoot out of there. #16 can also be removed at the top to get penetrating oil in the top, might not help, I can't remember... If the penetrating oil fails, then you can pull the whole spool out of the valve body and inspect/clean.