I've read some things that say instruments should be serviced yearly, but I can't understand why. If an instrument is reasonably well maintained then I can't imagine it would need servicing for a good few years. I have a trombone that is almost 20 years old, has never had anything go wrong, has never been serviced and it still plays as well as some brand new ones. The corks and felts may fail at some point, but I can just replace them when that happens. Should I get it serviced? Do others get their instruments serviced?