Here is my Meg playing Cnatural using the cross-fingering technique…
http://webpages.charter.net/rigby275/cnat1.wav
Here is my Meg playing Cnatural by half-holing the L1 hole…
http://webpages.charter.net/rigby275/cnat2.wav
Anybody have any suggestions for “tweaking” it a little bit to improve the sound?
Maybe you have already seen this. The link is way down on the first page of this website, so it gets overlooked. I’ve never tried tweaking a whistle, so don’t blame me if it doesn’t work. But if you are going to make a camp spoon out of it you might as well mess around with it first.
http://www.chiffandfipple.com/tweak.html
Good lord, there’s no tweak I know of that could fix that! 
Seriously though, you can tinker with it and see if anything helps. Make sure there are no weird things sticking to/on/in anywhere. Mess with the blade and windway. Stuff it with things. Sharpen and dull down things. Look at the link Cynth posted.
I love the sound you get by half holing - i want that whistle
i bet you can’t get a Burke to do that
For reasons I don’t understand, I couldn’t hear the clips. So my recommendation to tweak was not based on the sounds of the Cnats. It was just based on the idea that maybe tweaking would help. I have never tweaked either, just to complete my confession of total lack of knowledge here. 
Yeah, it kind of slides in and out when I try the half-hole method.
Marshall Amplifiers w/reverb
it’ll be fine.
I was always taught that the poor musician blames his instrument; the good musician blames himself. Repetition is the key to mastery. My advice is: drill, drill, drill!
It would take Jesus H himself or maybe Moses to blow a Cnatural on this whistle.
But on that other thread you said that one fingering method sounded good.
oxo xxx Wasn’t that it?
What he said, what he said, what he said.
Yeah, that fingering gives the closest to Cnat pitch that my whistle can make. I guess I could force myself get make do if it wasn’t for the buzzing rattly sound. Initially I thought I have a good solution because I was sort of able to tone a passable Cnat–however I soon found that when I transitioned to C from some other pitch like A or B I had the “loose screw” effect back again. Basically, I got my hopes up for no reason.
Did you look inside this whistle head to see if there is any bit of stray plastic? Or a burr?
And did you sticky-tac the whatzit in the windway?
There are tweaking instructions on here somewhere. Why don’t you try the noninvasive ones first?
Are you sure that you are blowing into the right end?
(Still loving the sound of you half holing - never fails to raise a smile)