Hi Roxy,

The ape I did in Solidworks, and yes print one out and let me know how it goes.

I took a look at your whistle design, How do you print it? I mean why do only half of the whistles work, did you check the warble on roundness, at what layer height are you printing?
You might try something I did with a ball-joint, so don't place the warble next to the wall but a little away from it and support it by 4 small pillars placed at the same distance from the centre of the warble so that the warble still touches the bottom in the centre. I hope it still makes sense, if not here is the ball-joint for clarification.