Heck, did some searching, and unlike modern welders, the AC225A is rated at 20% duty cycle, at all outputs... Now, I have Zero doubt that at 80 amps, you can probably run it close to 100%, but not according to the manual. I dont "think" they actually even have a auto trip duty cycle; meaning your warning is the burning wire smell
Edit: I know i sound like I have a grudge, and I Don't. I like the old Lincolns just fine, but compared to modern alternative, they just aren't a "good" choice for the money.
I often don't agree with 5030, but he's right on this; if easy replacement is a Key, HF is a good option. They are priced above the Amazon ones, and really very very similar, but returns/warranty are easier. Vevor 4 in 1, 185 amp, tig/stick/mig has been a good machine, and it was right around $200. Easy to use too.
If you go Old, transformer, that's fine; but you Want Dinse connectors, and dial adjustments, not taps.... Some old machines had a tap for 40, 60, 80, 100, 120, 160, 200. You want more selection; maybe 85 amps is perfect. On mig machines, some of the worst had Hi/Low and that was it....