Something strange has been happening on my horn for the past two weeks, and I'm wondering if anyone can offer me any explanations as to what is going on. The horn in question is a Yamaha Xeno 8335 GS that I've been playing on for about a year and a half. The horn has been great..no problems, reliable, never had to worry about it. The horn is well taken care of, cleaned out every month, oiled every day or every other day. Needless to say, the horn is in great condition. About a week and a half ago, I was playing the Hindemith sonata for my teacher and he was saying that my C#'s (4th space) were really sharp when they should be flat... I looked at my tuning slide and it was all the way in...I usually play with it out about a half inch or so..so I pulled it out to where i normally play. Ten minutes of playing later...its all the way in again. Today I noticed the same problem during my graudation ceremony and again during orchestra rehearsal tonight. Can any one offer me any ideas as to what is happening? I plan on going to Dillon's first thing in the morning to have it looked at and fixed. My second valve is also sticking for some reason, I don't know if that has anything tod o with it. I never place the horn on its second valve slide so I don't have a clue. Thanks for any of the advice.