Have you did a cyl test yet?
Your pump appears to be working for pressure, but you don't know the flow rate.
To test a cyl, you supply fluid to only one cyl at a time. Plug the other hoses
With the cyl fully retracted remove the base end hose and apply pressure to retract.
The relief may come on, but look to see if fluid continues to pour from the base end port.
If it does, then you know the seals are bad.
Do this for all cyl to check for cyl integrity.
To check the valve, you need a good cyl. Put a load on the cyl at full extension and put the lever to neutral. If the load descends, then the valve is leaking.