Any hydraulic cylinder can be repaired or rebuilt by a hydraulic shop. One that caters to farmers or loggers would be cheaper, probably better. Manufacturer may have a rebuild
kit. CMP should have parts
It sounds like it's wore out. Nothing should be loose. End caps usually are the bearing. If the rod moves sideways you should be loosing oil
. It also sounds like it could fail. I'd pull the cylinder and take it apart or take it to someone that can.
A hydraulic ram is just a smooth pipe with end caps, piston and rod. Usually they have o-ring seals
and the piston has one or more o-rings. Sometimes the rod will have a cup seal. You need to be clean and not get dirt, especially sand inside or it will ruin the seals
and pump. Reassemble with oil
on the seals and lube the cylinder with it. Bleed all the air out. If you don't get all the air out, since air compresses, the rudder
won't go all the way to hard over. Get a manual if you don't have one.
I have a Wagner and rebuilt my ram years ago. It took about an hour not counting extracting and reinstall.