step needs to be replaced and, depending upon how badly it's damaged, the bottom of the mast might need re-sleeving or building up of the step to compensate for what gets cut off to get it to undamaged material. The fixes might not cost more than $500, but our yard charges $20 per foot to pull & restep masts. The rudder shaft seal
looks like it must be letting water
in for there to be so much oxidation around there. Add maybe 1-2 thousand and change to drop the rudder and re-do it. Opening up these things is likely to uncover other items that also need attention. These boats are not reputed to be overbuilt. Are the decks all solid? Leaks
around port lights? Standing rigging
replaced since the '70's? Engine
maintained properly? OI 41's have been around since the '70's, so keel
damage from "navigational errors" involving rocks or shoals, along with hull
issues from "operator errors" involving docks or pilings are things to look for.