| If it's a standard Underwood (Underwood PT Ring?), you have to shim the space if it's to large. There are a few ways to do this, but the cheapest and quickest is to use the color-ad newsprint from the Sunday paper. Past experience with this -- it doesn't compress much, so once you have it fit, it stays pretty well. The more pro way of doing it is to use some thin wood, available at your luthiers or local hobby shop. Someone mentioned somewhere here, DonO, I think, that used sax reeds (YOU touch it) work well as they are wedge shaped and make it easy to adjust the snugness of the fit as desired. | 
