Okay heres some pictures
The adaptor which screws onto the can in one piece
Adaptor with the "tap" unscrewed
Inside the adaptor (part which screws onto the can) o-ring intact
The "tap" (the white stuff at the top is just a bit of masking tape i tried to use to make a better seal)
edit:
No air comes out the can when the regulator isn't attached, i'll go and try the water test, as its diffuclt to tell if its coming out from the bottom of the regulator, or where the tap screws in.