Relay clicks, gas blows, rollers dont turn

If it is an MiG welder, there are a few possibilities. 1- The roller traction adjustment of the feeder roller is incorrect or not properly locked. 2- Your weld makes the wire stick to the metal and holds back the feed causing backspooling. If this is the case, try increasing the welding amp or voltage.
3.-Low quality welding spool.

Does it snap or melt due to welding current?

both point to a problem with the welding gun/torch

tip
liner
damage to current carrying conductors

Are you using knurled rollers? Check the wire. Is it reversed polarity. Flux cored wire is very voltage sensitive.

Contacts of the main contact relay "CR-1" are likely fused together completing the circuit. Otherwise the trigger switch is fused closed.

The main contactor can sometimes be released, then dressing the contacts with a small point file (Small mill ******* about 1/4 inch wide and 1/16 inch thick.

Otherwise locating a contactor/relay of a suitable current rating with a control voltage/coil rating of 24 volts.

you can weld aluminum with the lincoln but you will need to change the liner in the wand to a nylon one and swich the gas to 100% argon and of course change the wire to an aluminum roll. and practice-practice-practice it is much more difficult to weld aluminum then steel and requires much more control.

First thing I would check is the relay that sends power to the transformer when you pull the trigger. That can be one of the hardest parts of a Mig welder to troubleshoot because you can read full voltage through the thing with a multimeter when the contacts are dirty and it's not functioning properly.

That's assuming you're losing power. If it's a feed issue then we can address that later.

lp

Your Linner of the gun could have a kink in it.

1/4" plate with a 135 amp machine is probably beyond it's duty cycle abilites. If you are using a mixed gas, and pushing the max on the settings, it will be cutting out because it is designed to.
You might want to get a higher amperage welder for consistent welding of 1/4"
The 140 Pro maxes out at 5/16" using inner shield wire. and 1/8", or 10 guage with gas.

a mig welder must have a good ground to work, also dont try using rusty wire it will jam in the liner, have you checked you are getting wire feed from the neck? just pull the tright and with the welder on it should feed out, if you can stop it its to loos tighten up the pinch roller, is there power on this wire feed? i have often seen new welders strick up the weld with to slow a wire feed and to many amps running, what happens then is it burns the wire away in one flash, right up inside the welding tip and every thing comes to a grinding holt then???? it can and often will just weld the wire into the tip,, witch may mean a new tip is needed, take off the shroud and try to unscrewing the tip if no wire comes out when you pull the triger
as the wire is stuck or welded to it you may be able to get it out still??? but its best to fit a new one in, go one size bigger than the wire your using at first as you are sure to get it very hot??? untill you get the hang of welding,,, use a good gas mix like argon light it will weld stanless steel as well?? but co2 works well on miled steel only, the problem with co2 is its a cold gas and you need a lot more amps to weld the same thickness of steel use it at about 2 to 4 psi only indoors, out doors use it at 4 - 6 psi and if out doors keep out of the wind as much as you can or it will only blow the gas away from your weld if that happens you cant weld without gas being there as a sheeld, dont try using a no gas welder they are like the devel having a bad hair day to use,
even a good welder wont like one? there c*ap!!!!
only try welding clean steel not rusty steel or it will spit like mad at you and you wont get a good weld,
if at all,,one of the most common fults that is
but i bet you have weded the wire to your tip?
its so easy to do at first,,only two word of warning
keep well raped up, sparks well fly and were gloves',,,
and keep your head sheeld on well over your eyes dont ever ever look at the welder when welding it will burn your eyes realy bad and you will wake up in the night feling like some git has just pored sand into your eyes and its going to hert like hell for day's,,,
i find the solor head sheel is far better, its nearly clear when not welding and go's dark in milliseconds you will like them as you can see what you are doing right up till you strick up the ark then it go's dark,,
most welders last for years iv had mine for the last 35 years it a clark 150 turbo mig, and iv doged it to death too,,,
the only thing that could realy go wrong inside them is the rectifier, mains coil or a relay,, not much left in it to go wrong ,
and now iv bored to death good luck with your welding ,,i hope this has helped you out

make sure rollers are clean and slots not wore out check alignment
do not over tighten wire feed so it smashes the wire
flux wire is hard to get a good setting
make sure if you can set it for gas welding it is not on this setting