Hey I was wondering how I can test the compression of the valves. Also if they are leaky. I'm thinking about valve rebuilding because my M series conn 8d was bought a few months ago and it was a school instrument. I like how it plays but I feel like there are things that should be done. The valves are one of them. So if there is any test for the valves please let me know. Thanks
If you like how it plays you might just wish to leave it alone. Anything you do is going to change the way it plays, perhaps to something you don't like. Check compression by pulling the valve slide part way out, wait a second or two and then push the key, as the air fills up the partial vacuum cause by pulling the slide you should hear a nice thunk. If there is no noise when you push the valve the air is leaking around the valve and that's bad compression. Another way to check is just slowly withdraw the valve slide. It should get harder as you pull due to the vacuum, if it comes all the way out it should pop.
