I have just bought a Santana22 of unknown age (suspect 23 years old). I've heard the keel bolts need replacing on this every 30 years. Can anyone tell me if these keel bolts look like they need replacing?

I've had this Santana 525 ('78) for less than a year, so I don't know its history. It has a wire-to-rope internal halyard, and the wire just got a fatal fray near the wire-rope interface. -I'd replace it with an all-rope halyard, but I can't do that without knowing what the sheave is like...