hi folks, my dad wanted some welding doing on some brackets so thought i would dig out the welder, (was fine the last time i used it) now no wire seems to come out of it, it will work sometimes but not others, i am in no way a professional welder been doing it as a hobby more than anything, im more used to arc to be honest. im welding box section steel that has a sort of zinc / carbon coating will migs not produce wire if theres a bad earth? dont really know where to start? any help you can provide will be gratefully recieved. many thanx in advance mark.