A few weeks ago, my trumpet started making a strange noise anytime I play the E on the top space. My professor and I figured out that there must be something loose that vibrates at that frequency and I've found that if I put horizontal pressure on my first and second valves in the direction of the lead pipe it stops. It's not really practical to do this anytime I have to play an E though. My question is what might cause this, or if it can be fixed? Let me know if anybody has ever heard of anything like this happening or experienced it firsthand before.