| Get a bunch of flat toothpicks, an X-acto knife, and some white (Elmer's) glue. Cut a bunch of the toothpicks to length (headstock thickness). Put them, all touching side-to-side, on a small piece of Scotch tape. Take that and drop in into the tuner hole, going around the inner surface of the tuner hole, and then put try putting the tuner in. Too loose? Add some toothpicks. Doesn't fit now? Take a few off. Once you have the correct number for a snug fit, glue them on the inside of the tuner hole. Let it dry, then install the tuner. Once the washer is in place, you'll never see the gap. Done. | 
