Tractor Repair: Case 970 Power Steering issues, mechanical clutch, hydraulic brakes

Question
I have a 970 case that has been parked for over a year due to engine trouble. I got the tractor from my father-in-law and fixed the engine but now I'm having an issue with the power steering. The hydraulic fluid and filter have been changed and all other hydraulic functions seem to be working fine. This tractor has a mechanical clutch and manual hydraulic brakes. I checked the circuit relief valve for blockage and made sure oil was flowing up to the steering actuator. I get a small amount of power to the steering at over 1500 rpm and moving. Any suggestions would be appreciated. I have no problem with fixing engine and mechanical problems but hydraulics seem to get the best of me.

Answer
  The hydraulic pump on the back of the tractor has two sections to it.  The larger section supplies the hitch and remotes, and the smaller section supplies the steering.  The steering section could be worn out and the rest of the hydraulics would still work OK if the larger section is still OK.  The pressure and flow of the pump can be checked with a flow rater, but because the pump is out in the open it's very easy to remove and disassemble, so it's sometimes easier and faster to do that instead of doing diagnostics with gauges and flow raters.  The fact that the steering improves a little at higher rpm's usually points to a bad pump.  Other causes are usually not affected by engine speed.