I bought my horn used two years ago and have always had problems with the valves. Recently, the 1st and 2nd valves stuck on the way up almost constantly. I got the pistons polished, the entire horn chemically cleaned, and the valves alined a week ago - and they're still sticking. There's also a black substance in the horn that turned up after the cleaning. I use Al Cass valve oil and do not apply pressure on the 2nd valve elbow. I just bought a Xeno C horn and cannot afford a new Bb. Thanks!