Hercules winch will pull until resistance

[Solo33]

The winch on my 230 timberjack. It will pull in cable but as soon as it hits resistance it stops. I've replaced the clutch pack seals and orings. I tested the pressure to the clutch pack that was around the 500-600 range. I did not test the brake side but it holds any load fine. I went through the clutch discs and they are dry, maybe a little glazed. Just wondering what my next step should be? A key sheared possibly? Thank you 

[Haleiwa]

Most hydraulic systems run 3000 to 3500 psi.  You have to suspect a weak pump or stuck relief valve.

[OntarioAl]

Solo33
Hercules winch pressure 450 psi (both brake and clutch) 500 to 600 is on the high side
Steering and Blade cylinder 1750 psi
These are from the Service Manual
Listed as clutch slipping (failure to pull)
1/grease on clutch plates  (degrease with a strong detergent)
2/defective seal #200236  (avoid over greasing)
3/oil in clutch plates          (clutch cylinder leaking replace seals degrease or renew plates)
4/ clutch plates glazed or rusted (rough with file or clean with emery cloth maintain flatness)
5/ dirt in clutch plates (clean)
There is a procedure when installing the clutch pressure plate to adjust the travel to .070
did you follow it?
Hope this helps
Cheers
Al

[Solo33]

I still have the plates out. I'm going to run some Emery cloth over them. I have the service manual here to go off of when I put it back together. The blade will pick the front up and the steering is fine. So i would think the pump would be fine. 

[Thompson8821]

What's the procedure to installing the pressure plate? Also where are you adjusting to .70 the four bolts?