Forget the copper tape around the posts being a good solution - it worked for the bridge but not the stop piece, which slowly pulled its posts out of the guitar.,

So now I'm gluing veneer shims in around the sides of the post holes. I'm not trying to do it all at once, so far I've glued in four pieces of veneer, about 4mm wide, around each hole. I've now got to go back and glue some more in the gaps left. It's a lot easier than trying to do it all at once with a single piece of veneer.