and3/32 of an inch is 2.38mm or as you said .24 of a CM.
I stand corrected3/32" is 2.38mm. It is a big hole when compared to the spec, which is 1.2mm. That's twice as big.
Like I said, "There is something about inch sizes I never learn to understand!"
I have 2 Spheroid which I am very happy with. I've never had the need to make the air hole bigger.
Maybe there is a little burr in the air hole in the deck or 510 connection.
It does not take much burrs to create an obstacle to the air.