Need some Mig help.

My son bought a Northern Industrial 125 welder some years ago, been sitting in my garage doing nothing for years.  He bought a house, I get my garage back.  Though it's ~8 years old, it's only got a few hours on it.

Welder is no longer carried by Northern Tools and they have no reference for parts.  Problem is the thumb screw that applies pressure to the .030 wire is pulling out of its plastic fitting.  It's a 1/4-20 bolt, head is encased in plastic, thumb screw applies pressure.  It won't deliver enough pressure so I used a small C-clamp to pressure it; slips, add a little more pressure, slips, little more, the tiny motor won't drive it.  You can hear the motor straining while not moving the wire.

If you have any suggestions to MacGuyver a fix, I'd love to hear them.

Thanks, Dan

Northern Industrial 125

I doubt the real problem is with the thumbscrew.  The gun liner is bound up, or the tip is blocked, or something. Has it sat long enough for the wire to rust into the liner?  Start by pulling the gun apart, and work your way toward the machine.  

It is likely the gun will be a standard part, like a Tweco.  Also likely the welder will be a rebrand, so Miller, Lincoln, or some Italian brand.  Do a bit of googling, and you can probably figure out it's heritage, which will allow you to find instructions and parts.

yes.. I'd check the liner.. 

OK, thanks.  Cut the wire and pull it out the nozzle and feel for snags?

Cut in machine  by the spool and pull it back from the cable. Check the wire on the roll in the machine. If it's all rusty just get a new spool.

Wire's clean and shiny, newish.  Is there an identifier to the manufacturer?  It kinda sorta looks like my Hobart 135, but at this level they all kinda sorta look the same.

Does the roller have more then one groove?

Many MIG welders can use more then one diameter wire:

0.023, .030, 0.035, some are solid and some are flux core but you need to use the correct groove or you may have a problem similar to what you're having.

It's got two, it's on the correct one.

FWIW, you can get a whole new gun assembly pretty cheap. I bought one off of Ebay for my Lincoln 125 and have been very happy with it. 

try going inverted

I have had to unseize the upper roller on a couple of occasions.