Deere 1020 no hydraulics when clutch disengaged

Hello-

Looking for someone to shed some light on this--

On my recently purchased, '68 1020, open center system, 8 piston pump:

I have no hydraulic function anytime the clutch is disengaged.

When clutch is engaged, I have some function, but not very good... The loader operates, but is sluggish and very weak, 3pt lifts my grader blade fine, power steering works.
It acts like the front pump just isn't getting enough fluid to do anything. I think its providing some pressure, but not much.

So far I have:

-Replaced the intake screen, transmission filter, and pump screen. All pretty clogged, but did not solve the problem.

- Checked the oil return line coming out of the top of the front reservoir. With transmission pump operating, it is easily pumping the specified 1gal/10sec out this line, so I know the reservoir is getting filled.

-Ran the stroke control valve in as far as it will go. No effect.

-Removed and looked inside the hydraulic pump. Nothing broken, very clean inside, virtually no wear on any parts...it looks like a new pump.

Any thoughts? I'm getting pretty frustrated with this machine.

Thanks