Removing the rudder is not hard, but more work than it's worth unless you have a reason.
I had a little bit of play at the lower bushing, and the top of the rudder was rubbing slightly against the hull flange. The drawing in the manual was a little unclear to me, so I decided to do it. When I hauled , we blocked the boat pretty high up. (Less of a hole to dig in the ground to have room to remove it.) We supported the rudder and I removed the steering cables and disassembled the quadrant. (Found a few broken strands on my cables that you would't see until cables are removed). There is a hefty bolt that goes through the rudder stock and the quadrant that actually holds everything "up".
I am sure this had not been apart since 1988 at the factory, and it says a lot for Ericson quality that antiseeze had been used on all the SS bolts that holds the aluminum quadrant together! Everything came apart nicely.
The quadrant rides on a plastic washer on top of the two brass rings you asked about. This is the stuffingbox that keeps water from being pushed out the top. I had three rings of packing in excellent shape.
There is a second grease fitting for the bronze bushing that holds the top of the rudder stock in place. This bushing w/housing is bolted to the underneath of the cockpit sole, and the grease fitting ends up between the quadrant and the sole. A tight fit and a long reach for the grease gun!
I had looked for this in the past, but did not find it until now.
The lower "bearing" is nothing but a bronze bushing either glasses or glued in the rudder tube. After all this we decided not to remove it. After looking at the design, I'm convinced the rudder wont go anywhere!
I had the yard build up a little layer of glass where the rudderstock meets the hull. (Should be a plastic washer here also).
On this boat the grease fitting on the rudder tube itself is above the lower bronze bushing. There is quite a bit of "volume" in the tube, so it took one and a half (!) tube of grease before anything came out the bottom!
This job took care of the rubbing between rudder and hull, somehow the play disappeared (partially new "wear" surface on rudderstock?) and gave me piece of mind.
Jon