Atlas 1302 only working on high RPM

Hello, i couldn't find any better forum to ask this. So basically I have 1988 year Atlas 1302 and it doesn't move it's arm on low rpm, on medium rpm it moves a bit and stops, on high rpm it works, but still when I pull lever it takes a few seconds till it starts to move. What is causing this and how to fix it? Thanks for answers in advance.

[Atl]

Serial number please.

You need to check pilot pressure.

I think this: 132M19027

[Atl]

Main pump picture please

[Atl]

Do you have any manometers?

Yes, but I found small broken bronze rings in hydraulic pump. :(

[Atl]

Where? Send picture please