For a tiller go to any home center or hardware store that has a metal rack and get some 7/8″ OD aluminum pipe. Cut it to a length you feel would be best. I don’t use the word rare often but, the rudder assembly is rare, on a motor, or just the parts.
Here are a couple videos on repairing the coil or you can use one of Richards replacement tubes. https://youtu.be/xwbTlC1xIlA?si=craDOGpo5SrZT8q9 ——— https://youtu.be/e2vxDqF_OEU?si=MlK5C0AmKlYX4-S1
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.