I have an Aristocrat alto that produces a buzzing noise at certain frequencies. I can't find any metal-on-metal contact points anywhere (hinge tubes, keys, etc.). I've did everything I can think of to track it down like touching all the rollers, keys, hinge tubes, guards,.. you name it. Which leads me to suspect one or more of the snap in resonators might be buzzing. Does anyone know if this is a fairly likely culprit? I did find a couple without disassembling the horn that you can spin with a dental pick so I know there are at least a couple that I did not get enough shellac on the spud before snapping.