I have an Olds flugabone, which plays nice enough, but the sound is very dark and it doesn't play as loud as other instruments. It's technically called a "marching trombone", but wouldn't a marching instrument be pretty loud? The instrument is pretty old and beat up, and when you pull the slides, it doesn't hold a vacuum very long or at all, so the valves are obviously worn.
So my question is what are the effects of worn valves, and what is involved in fixing that?