difficult to understand your scenarios because we're missing data:
1. don't know exact model of your torche
2. or if it even works properly, does trigger button work in "normal" DCEN mode for welding steel?
3. photos of cables coming off welder and how they're attached
For your lathe gears, why are you brazing instead welding? Is it because it was originally brazed on? If brazing was to keep heat down to prevent distortion, TIG brazing won't reduce temps in HAZ much compared to TIG welding anyway. To keep heat to minimum, you'll want to use gas torche.
Link to original page on YouTube.
Gas brazing's only way to keep heat low and join thin heat-treated chromoly or *crom tubing (some of this is just 0,4mm thick!). I prefer smooth fillets, lighter and transmit loads across cleaner.
