Tractor Repair: 3 point hitch slow to lower, hydraulic control valve, emery cloth

Question
I have a case 990 that sat outside for 10 years before i bought it.Ichanged all the fluids and filters before i used it and it worked great for about 60 hrs. Now the 3 point hitch is very slow to lower and when you have an implement on the back it constantly leaks down about 2 inches and then recovers itself.Very annoying when driving. Some one suggested the 2 valves under the plate behind the lift levers might be stuck ,but i checked them and they seem okay.also the knob that controls the drop rate doesn't, seem to have any effect no matter where you set it.any ideas . thks. neil

Answer
Hello,

  You will need to check more than just the 2 valves under the plate that you mentioned.  In the hitch control valve, there are about 7 or 8 different spools, plungers, and springs.  Any of those could be sticking or have dirt stuck in them, or have a bad spring.  You can see a breakdown of the valve by going to servicemotor.com, clicking on "parts", then "look up your own parts", then Case Ih.  In the search box, type in 990 and click search.  In the results, select the correct type and serial number range.  Scroll down to the hydraulic section, click it, and then select "hydraulic control valve."  You will see the entire valve with lots of spools and plungers under threaded access plugs.  Take everything out and wash it, and make sure everything moves freely.  Sticky spools can be polished with fine emery cloth.  Inspect all spools for plugged orifices, and check for broken or collapsed springs.

                       Good luck,

                          Arnie