Apologies for the previous 'smelling' and grammar but I have seen that Therapy sell a probe entry system that is basically a flap of plastic in white or black. Before you insert the probe you have to lift the flap 'clearly stating the gas type' and if they are lost from there then give them a cigarette and bottle of o2 and sing a song.
good luck
Paul


ERRATIC MEANS STATIC SO BE ERRATIC AND NOT STATIC
WE ARE ALL IN THE NHS AND THIS IS
"ERRATIC AND STATIC"