I did that and I found nothing a couple of threads about it but no maker or anything all I know is what's on the back made on Denmark 90 amps and house current
Good luck, finding info on those older, obscure make or one off machines, especially mig machines is very difficult in my experience. It's one of those things that you just accept and move on.
I don't know who MADE it or what AMW stands for, but I can tell you who likely SOLD it: Snap On. They were importing them from Denmark in the 80's, maybe into the 90's, and might still have at least an owner's manual to send you.