XB-40 in C: high notes squeaking?

["Laurent Vigouroux" <laurent.vigouroux@xxxxxxxxxxx>]

Hi all

I've just got my XB-40 in C and I have had some trouble bending the holes
above 7. The notes squeak. It's even worse for the 10th hole where I have to
shape my mouth as for bending in order to obtain a note.

I'm a little bit surprise as I'm not too bad at bending and overblowing.

Is it only a technique problem or can I do some tweaking (gapping?) to
improve the response?

Thanks for your help

   Laurent