I have been recently working on projection and long tones to good effect. When I play low C, well supported with a column of air, the tone wobbles up and down wildly of its own accord. This only happens with low C. B and B flat sound great. I have just had my tenor overhauled. Is at a leak or is it some sort of resonance taking over my sax (which is what it feels like). All other notes are fine. I am using an Otto Link Tone Edge 6* and a Rovner ligature. Thanks for your help in advance.