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Evening guys thank you for the add,

Urgent problem Zill 131 power steering issues ... need to use the truck this weekend so hoping for some advice...

It's got new oil in it, the old oil didn't look like it had gone bad. It flows around the system fine verifying the pump is ok and not at fault. The arms and links on the steering move as they should so points to the steering box not controling oil flow correctly. A steering box is usually one job I would leave to the professionals.
It doesn’t seem like the the hydraulic metering valve is sending oil to the hydraulic assist part of it and just dumping back to tank.

Any help greatly appreciated

If you've drained the oil it will need to bleed the air out of the system, start her up and let her idle, turn the steering all the way over one way and then all the way the other way, you'll need to do it for a while to clear the air, also just check with the engine running that you have enough oil in the reservoir, if not it'll suck air back in, needs to be fill almost to the brim to start with.