Greg,If you don't see any play in the shaft as I described in my article for NPOA and there is no play in the rudder itself, then check the Edson steering cables. Every few years, depending on how much offshore sailing we have done, I have to take a few turns on the steering cable turnbuckles to make up for stretch. When the cables begin to get to loose I can hear a thump in the stern when the stern is lifted by a quarting wave. It's sort of unnerving to hear the thump late at night, miles offshore, and just sit there for hours wondering if the rudder is about to leave the boat. I pay lots of attention to the rudder.