Playing the 2nd Octave on the Tin Whistle help?

Try a Clarke sweetone or meg, but also tweak your oak. I got a feadog that was unplayable out of the box, particularly in the second octave, but after tweaking it it’s my favorite. It’s simple, just the putty trick will do. But breath controll makes a big difference too. Also, playing enough at one go- maybe 15 min or so- to get your whistle (and yourself) warmed up really helps.