Re: Need some steering expertise.
Well, I confess I'm totally unfamiliar with that particular system, but I can tell you that those are what are called "unbalanced" cylinders, meaning the rod only comes out one end. Therefor, the displacement inside is greater on one end than the other because the rod partly fills one end. No big deal, except the unequal displacement will make it steer faster and harder in one direction than the other, which will be slower and easier. Also, the oil coming and going from the ends will be greater on one end than the other. This means the helm must be capable of constantly adding to or getting rid of the excess or shortage of oil as you steer back and forth. The unbalanced design is normally not an issue because they are mounted in opposite directions and cancel each other out.
I said all this simply to say that I don't know whether or not your helm is capable of doing that. So, your first priority must be to find the answer to that question. My gut feeling is that it is not.
I can't believe the cylinders are single action as you suggested. My guess is that they are double action (work in push AND pull direction). But as I said, I am not familiar with those particular ones.
IF, IF, the system is compatible with single cylinder operation, I would have to agree it probably needs to be filled and bled.
My qualifications: I worked 20 years in a plant that builds marine hydraulic steering systems. But I didn't build this one.