I have a brand new Kerry Pro whistle with what appears to have a stuck tunning slide. I assume it is cork like on Chieftain whistles. Does anyone know how to get it unstuck?
My experience with stuck joints on metal instruments is that gentle heat works better than anything else. Gentle, like a hair dryer on medium for a few minutes while pulling gently on the parts with an ever so slight twist in one direction. More like a little pressure than a twist. A helper is a good idea. One applies pressure and one uses the hair dryer. And a little whiskey to share can’t hurt. If it is cork and you damage it, it’s a pretty easy repair job to replace the cork. Don’t use any solvents IMO and for sure don’t flex the joint. 
Asking the maker, especially since it’s “brand new”, often gets good results…
Best wishes.
Steve
Send it back to Phil Hardy, sorted my Chieftain out F.O.C even though it was secondhand and I’d bought it elsewhere
Thanks ecohawk! That worked. It turns out that pretty much what Phil advised, too.
I sent a email yesterday and had a reply in my inbox this morning. Much quicker than I had expected.
“Warm it up so it is warm to touch then turn the body whilst holding the head very tight.
It’s as if you are unscrewing it.
It should come slowly apart.”
It’s actually metal on metal with no cork. Lovely whistle!
I thought that aluminum against aluminum without an insulator like teflon tape was a “no no”? 
don’t they usually have brass slides?
I don’t think there is a problem as long you reapply some grease when you reassemble it. This is kind of an old-school design, but I wanted the sound, so I am happy.