I’ve finally plugged the holes at the aft outer corners of the saloon, which had been left unplugged since the new corner posts were installed over 14 years ago. There are three holes to plug in each post. I bought 1/2-inch teak plugs for this, but found that the bottom hole on the starboard post was larger by far. Having nothing on hand that exactly fit the larger hole, I took a bigger teak plug and sanded it down to size.
I shaved them down level the next day and lightly sanded them.