I tried sticking the end of a paperclip into the airflow control but it doesnt work

it cant go through/deep enough twist it off!
Just tried freezing it for 10min but the thing just wouldnt budge :/
Sorry..
Remove the tank and coil/head.
This should leave just the "base" attached to your battery.
Try to unscrew the base using the "lines" as grips.
If that fails,
invert the unit and sharply tap the "base" on a hard surface/kitchen counter a few times. (think packing a new pack of smokes) Try to unscrew the base using the "lines" as grips.
If that fails,
You should be able to rotate the "ring" so that the window is completely open on both sides. Insert a thin rod, tool, fork tine, (I use a Green base luer lock blunt needle (gauge unknown) so it protrudes from the other side. Try to unscrew the base using the "lines" as grips and the tool for leverage.
if these fail...it's time for a clamping tool on the "lines".( damage may result)
Cheers
I