Welcome!
Hey Mike - I'm a fellow O'Day 20 (75) owner in NC - welcome to the club! There are a lot of things to check, but based on my own, past experience, I would check all of the standing rigging. Not knowing the long term history of the boat, you really have no way (unless you were told) to know the condition. I ended up with a lower shroud that gave way, and while it could have been real trouble, it just turned out to be a big scare. I'm in the process of replacing all 6 cables.My rudder pintles were pretty worn, and one gave out on me. Basically check all of the stainless hardware for any cracks, pitting, etc. If it looks questionable, I'd replace it.My centerboard had a lot of buildup on it, so once splashed, I swam down and gave it a good scraping - goes up and down nicely now.There's a million other things, but those are some of the early things I'd look at.Best of luck!Tom