Hi.I own a sealey 170/1 mig.Theres no gas coming out of the torch. Have checked,plenty of gas in bottle,taken of the pipe gas coming out through the regulator,suspect that there is a type of switch within the welder,doesn't look as though there is a switch on the gun,have also checked the narrow black pipe which delivers gas to the gun all is intact and in place. Any help would be greatly appreciated Thanks Mike.