Without a blowtorch, I must say that the Rounded type Vapalux/Bialaddin air screws are a pain to remove, but I managed, with a small vice, several size pliers and some gripping rubber. The old hands are aching a bit now! Just soaking in some cleaner!
A useful trick is to use a small screwdriver or similar tool passed through the holes in the air button as a tommy bar to get it moving.
Yes, I generally use the shank-end of a close-fitting drill-bit. They're possibly a little brittle but I haven't managed to snap one yet. A length of mild steel rod of the correct diameter might be better but I suspect that would probably bend given the torque that sometimes has to be exercised. As a general rule, I leave them alone unless there's no alternative...
I took it off because the ventilator was a complete wreck. I found a small bradall which is very strong and works well.
