I have Super 55, 1955 model year. Last year I rebuilt the hydralic pump and replaced all seals in the hydralics including the cylinder. It works fine picking up implements now but fades once the tractor warms up. It dosen't fade when cold that I can recall. If I turn off the tractor and leave the implement raised off the groud they stay raised for about an hour or so with the tractor warm or cold. I'm assuming I have a leak in the hyrdalic valve or it's worn out as this tractor has alot of hours on it. I do have a parts tractor with low hours and my thinking is to swap the hydralic valve but need some advice here. 

 The second thing I was thinking was the hydralic fluid is to thin. I'm using Napa's universal hydralic fluid and it's very thing when warm. I had read in a prevoius post but can't find it now that I should be running an Agco hydralic oil, can anyone tell me the type so I can get that?
  
Also, I had read somewhere I should install a longer pickup tube for the hydralic fluid, does anyone know how long it should be? 

Thanks
Eric