Does anyone know how to go about fixing a sticky foot control valve on the 320D whether its cleaning it, getting new seals, or a whole new block or rods. The issue is when trying to lower the boom it sticks too much and when you finally press it to the point it moves it goes hard to the ground. Cleaning it up and using some lube seemed to help a little but unfortunately can't get it to improve further and its a pretty big safety hazard. Machine serial # 1T0320DAHDG239479 pictures for reference: (the compartment was packed with dirt so the wet areas you see are just water or a degreaser)
If you disconnect the linkage from the spools, do the pedals work freely?
Yes, while manually pushing/pulling the rods on the valve box(I don't know technical term for components) we discovered that is where the sticking appeared to be coming from. I also forgot to mention that the issue is most noticeable when lowering boom, its significantly less noticeable when tilting or raising.
Then there is probably a rust and scale build up under inside the spool caps. Or your lockout solenoids are not releasing all the way. They are screwed into the spool caps (which are on the opposite end of the control valve from your spools).