My rudder has needed an overhaul for a long time. Almost on the first day I nearly cut one of the control lines off by dropping the blade and catching it between the blade and stock. Perfect guillotine. I have had a knot in the line ever since. There is also a nasty notch in the trailing edge where it has hit the transom when raised.
The whole rudder head also moves back and forth too much. It swings on two machine screws. Each only moves only slightly, but they move in opposite directions, which doubles the effect. For a long time I have wanted to replace them with a single threaded rod, acting as a long pintle through both fittings. I have now done this, with less effort than I feared.
I have used nyloc nuts on an 8mm threaded stainless steel rod. Getting it up through the bottom fitting was straight forward. Lining up everything to get it on through the upper one was much harder, as everything had to be perfectly in line and the rod tapped through with a mallet. Initially I just could not line everything up. Then had a brain wave. Fitted the upper screw back in place, from above. That held the top parts in line. Then I tapped the rod gently upwards. It pushed the screw up and, as hoped, it followed the screw through and popped out at the top. One more tap sent it up far enough to get a second nut on top. All now swings nicely, with much less play. Rudder blade next.