what the position that your selector switch put on ?? "0" position ?? i think you better measure you machine output voltage from the torch (+) with respect to earth (-), there should be 17 to 40 volts something, if there have any volts output more than 17,18 and your could be weld in nodoubt...
the wires that you regard are the feed back cable, they could not be disconnect, if disconnect will making the power source get down. you need to connect them back.
the output you check should from 18-34volts if working normal.
if there have any 'tik' 'tak' sound while you trigger you torch...
you can try to check the feed motor voltage first while you trigger the torch.
if have voltage get in to the feed motor, that mean your feed motor get dowm.
is that the step controller mig machine.
if the machine is thyristor type, maybe the problem occur from the scr device or pcb board.
also you have to check you mig torch first with the good one.
take off your torch from machine first, then turn on the machine.
if wire stop feed, that mean the torch problem.
if not, that mean the machine in trouble. mostly the problem in pcboard.
nowaday, most of the china welding set had put the footpad option in their machine; the long run or called duty cycle should depend the ampere output of the power source, and also the material thickness that you weld for.
you need to exchange the steel linear to teflon linear inside you mig torch, and the feed roller should use the u type shape, the original one was the v shape, but you can used the v shape roller also.