Let me throw in a question to piggyback on this excellent thread. I have a set of Tony DIxon WHistles recommended by Leadfingers, and by and large I really love them. The last couple times I have played the g whistle though in a session I have noticed the upper register has flaws in it, ie with the same amount of airflow on any other whistle it would easily play well in the upper register, but this G won't hold the register playing quietly. It is not related to technique as it didn't happen a couple weeks ago asn it only happens on this whistle. Could this be related to crud in the fipple or something gross like that? How frequently to you clean your whistles? i am sort of a newcomer to the instrument so be gentle with me!   Thanks jimmyt