It’s a 33 year old boat. And has wooden stringers. Even if it was five years old, always be something to fix. Trust me, I know from experience.
Start with a light sand to open up the grain of the wood. Don’t go heavy grit. You want a ultra smooth finish.
Then go buy the three step teak oil kit from Starbrite and follow the directions.
(Cleaner, brightener and oil)
Just be generous with the oil and keep applying till it doesn’t absorb anymore.
Will be beautiful with just a few hours work.
Then post pics of before and after.