Keel centerboard
Your centerboard should go all the way into the keel on your 23. If your 23 was built before 1974, the keel and centerboard is made of cast iron, otherwise if you have a later model 23 the keel is lead and the centerboard is made of Fiberglass. The O'Days 23s with cast iron keels had problems, so I've been told. At any rate, if the centerboard isn't going all the way up, there must be something preventing it from doing so.