Often when I play my pipes the low F# and E keys will not produce the correct tone. Instead of the desired low note emitting from the chanter a high pitched harmonic will sound instead and this detracts from the music being played.

I have tried changing the pads on the keys to ensure that the holes are properly closed but to no effect. I have also adjusted the key movement to ensure that the openings have sufficient ventilation for the notes but it has made little difference.

I have no problem with the low D key or with any other keys on the chanter. Does anyone have an idea of what could be causing this problem? I am an instrment maker and capable to rework the pipes but I simply don't know what to try next. Any suggestions welcome. Thank you.