Case 485 3pt hitch problem

[tryan34]

I recently purchased a case ih 485 '88 model year, after changing fluids and filters the 3pt hitch is not working correctly. It works fine with no load, but with weight the arms go up but will not go down. As soon as the weight is off they work again. Tried the draft control, the speed control, and the external hydraulics. I'm stumped...