Hydraulic issues on 1010 crawler/loader

[JAJ]

Hydraulics on this machine will only create 350psi.
Machine has #810 loader and #35 ripper.
The bucket will go up about four feet off the ground and stop,
it goes down and will just start to lift the tracks and stop.
The ripper goes up all the way and goes down and starts to lift the track and stop. The bucket will fully curl and dump but very slowly.
I have installed a pressure gage on the cylinder extend line (cause it was easy to get at) of the ripper and that is where I get the 350 max psi.
Here is what I have done so far:
1 Rebuilt the “Webster” pump per service manual
2 Replaced 90% of the hydraulic lines. The main steel lines going
and coming from the pump are still original.
3 Drained and clean the tank. Replaced the filter and inspected
and clean the strainer/screen. Also cleaned and inspected the
pop up indicator piston mechanism per the manual.
4 Flushed the system using diesel fuel per a previous note from
Lavoy. I was careful not to operate any hyd valves during this
flush. I ran the engine at 1200 rpm for 1.5 hours. Drained out
all the diesel fuel, cleaned the tank, replaced the filter again,
cleaned the screen again (looked good) and filled the tank with
new hydraulic oil.
5 Fired her up and I get only 350psiy

I am suspicious that my problem is the relief valves. The manual
shows three separate relief valves and how to clean and inspect them. Manual shows one for boom, one for bucket and one “anti-cavitation” for the “SYSTEM”. No mention of a relief valve for the ripper.
My question is >>> seeing how my low 350psi seems to be typical to all functions would it make sense to pull out and inspect the SYSTEM relief valve first? I have no idea what cavitation means but it appears to be the culprit. I have never worked on hydraulics before so I’m not looking forward to pulling out all three relief valves if I don’t need to.
Thank you for any ideas you may have.
Jim Johnson