The hydraulic fluid should be AW68 not AW32 and the hydraulic pressure is 2900 PSI. I would try lifting a 3000# load and see if it will pick it up in the free lift stage. If it does then the pump should be good and the secondary cylinder(s) must be repacked. If it doesn't then either the pump is no good or the relief valve is set too low. The relief valve is located on the underside of the control valve and is covered with a plastic boot.
In all likelihood the pump is the issue since you said the problem is worse once the hydraulic fluid heats up.