Hello all! I am hoping I can pick some brains here.

I have the manuals but I am at a point where they don't really help me anymore.

I have resurrected this hyster after sitting for about 10 years. Changed all the filters and fluids. Ran and worked great for about a month. Now, it will lift and tilt when first started, but will get slower and slower irregardless of engine speed, till they stop working. Takes about a min or 2. Steering works the same throughout. I drained the fluid thinking maybe the in tank strainer was clogging up, as if you let the lift sit 10 min or so and restart the forks will work again, although the same as before. No change. I adjusted the priority valve on the pump, but I have to go all the way to the fork side, and steering won't work. The forks work great for about 5 min, then start to slow down again. There is no happy medium I can set it so steering and the forks work.

I'm kind of stuck now, thinking maybe something in the control valve, I don't think it is the pump, as the steering is good throughout and you can drive it around steering back and forth and it stays the same.

Maybe take the priority valve out of the pump and clean it?

Any thoughts would be greatly appreciated.