Having trouble with my 3 point hitch. Went through it put a rebuilt pump on but still having the same problem The arms go up fine. hold any position. I installed a new piston and seals. Problem is after a short time they do not want to go down, I shut the tractor off and let it set for a couple of hours and they bleed down slowly and then start the tractor up and they again work fine for a while then stick in the up position again.