I have a Selmer Paris Series 3 that I got about a year and a half ago. Recently I've had trouble with my G and G# with octave key pressed not responding right. I'm not sure how to explain it but it's like the note bends and does a multiphonic of the low G and high G. My teacher played on my horn and had the same problem. He said he's not sure what causes it but he knew one other person that had the same problem, I don't know their instrument model or anything. Thanks for any help.