The rudders on your boat were only produced for a short time, you won't be able to get spares. The current style lift automatically if they hit anything. And yes, they must be locked hard down to negate heavy helm.
Near new set of Redhead sails, $1200. Good used set, $800, will separate, ie, mainsail only, near new, $900 and used, $600. Rod could have a look at them next time he is up, or, at Oberon in a few weeks.