Some of the earlier torches had a wire doing nothing...just sits in the torch handle not attatched to anything If there's no spade connector on the end it sounds like that type.
weldequip
Press the torch trigger & see if anything happens with it loose.
It may need to be touching the main copper power cable, or the trigger contact, can't tell without seeing it.
weldequip
My ancient & now defunct SIP is the same.
I think - but stand to be corrected, that for the Gas only models they used a single trigger wire that connects to the torch supply via the torch metalwork when you press the trigger, but they couldnt do this for gas/no gas models as the polarity has to be reversible. In this case they need 2 wires for the trigger so it operates independent of the torch supply. So they use the same torch in both, but leave the unused wire floating in the gas only models.