My flute is quite new, just bought it in the summer, but when the key covering the Bb hole and the key covering the hole above the F key lift after being pressed it makes a little click-y sort of sound. Not an actual click, but a funny 'tzip'. I know it's only minor, but it's very irritating and I wondered whether anyone knew how to stop it.
Is it comming from the mechanism, or is it a sticky pad? If it's a sticky pad, it makes I sound as the pad lifts off the tonehole. A technician could easily solve it. I have had some success using a sheet of cigarette paper inserted between the pad and tonehole. Try it dry and press the key down on it a few times. Don't drag the paper between them. If that doesn't solve it, you can try dampening the paper in rubbing alcohol, but don't soak the pad and do use a dry paper right away to dry the pad surface. Ultimately, a tech can change the pad if necessary.