Most of my problems with note production and squeaks happen when I play a D or D# (+octave key) coming from C# below on the alto. What I'm trying to do now is play those notes over and over. From the high E on, it's smooth sailing. The biggest problem is C# to D, or most notes in the low octave to D and to a lesser extent, D#. If I start the note on the D+octave, it's better, but still not as good as other notes. I've also tried different reeds (synthetic and cane) to see if that matters, but it doesn't seem to.