*winces* Ouch. I'm a woodwind player instead of a brass player, but I think I kind of know what you're talking about. And I can sympathize. My junior year of high school my band was doing a 'Grease' show, and my lyre loosened the ring at the top of the bottom joint of my clarinet that it fell apart right there on the field. Fortunately we were at a part of the show where I was able to pick the bottom half of my horn up without being noticed, and I just BS-ed my way through the rest of the show.