Yup some whistle some don't.Yes, I should have paid a bit more attention, since it was an under $10 clone.The airflow is on the side, but I think I will take that screw all the way out. I keep hearing a whistle and wondering if that is what is causing it.
1. Take out the screw and the whistle should stop. Also look inside to see if there are any burrs in there that might cause the whistle.
2. Some wrap plumbers tape around the air flow screw and put it back in the hole.
3. You can take a Dremel or drill and chamfer the airhole a bit to get rid of the hard edge.
4. Some put a little piece of mesh wick in the hole to stop the whistle. Don't push in too far or it will short against the center pin.
5. Pick up another clone, Tobeco or EHPro.