CT520D power issues

[brandonsmash]

Man, today's been kind of lousy and it just culminated with a failure on my Everlast CT520D box when I went to do some TIG welding I'd been anticipating all day.

This is one of those ubiquitous 240V Chinese DC Plasma/TIG/Arc boxes. It has been really great to me over the past couple or three years I've owned it.

Last time I used it was a week or two ago, and I used it to run some stick on some steel. Nothing new, nothing challenging or very high-amperage, nothing over the duty cycle, etc.
I went to turn off the machine when I was done but it wouldn't turn off. The switch wouldn't depress to the off position, and the machine stayed running. I tried several times but it simply would just rebound and never interrupt power.

Okay, weird, but no big deal: Just plug/unplug the machine from power when I want to use it and fire in a new DPST switch when I get a chance, right?

Today I plugged the machine back into the outlet and POP! goes the breaker. Huh!

I pulled the cover off and checked for obvious shorts or faults (bulging or wet capacitor, blown resistor, etc.) and saw nothing obvious.

Checked my power, reset breaker, tried it again. Breaker trips.

Next I disconnected power and unplugged the switch. I pulled apart the switch and cleaned the (slightly scorchy) contacts and reassembled it, testing that it toggled (yes it did). Plug in power to the switch, turn on breaker, no problems. The switch LED comes on. Disco the power, reinstall the switch, attach welder power, on: Breaker trips.

Okay, wtf?

I pulled one pole of power from the switch and turned it on: No problems.
I swapped power poles on the switch and turned it on: No problems.
Attach both power poles and turn it on: Breaker trips immediately.

The next thing I did is disconnect the sub-board lead and test. Breaker still trips.

Now here's where it gets ****ty.

I pulled one of the two power leads (four yellow wires, two each red and black) and promptly shocked myself a bit. Oops. I grabbed my multimeter and went searching for voltage and stuttered just a bit. . . and jumped the power poles. POW! Well, the mini flash-bang stunned me for a second. It definitely scorched the connection. Stupid me: I wasn't thinking that connection was powered by the capacitor bank and it was still live.

Well, wtf do I do now?

I still don't see any obvious problems, except now the scorch marks where I quickly discharged a capacitor.

Has my beloved combo box cut its last piece of steel? Did I kill it? Am I overlooking something obvious? I'm generally pretty decent with electrics (seeing as how I'm a mechanic and work on electric hoists) but I'm unfamiliar with most of the intricacies of welders, particularly the inverter-style. Any input would be super-appreciated.

[brandonsmash]

No love?

I've been half looking at the AlphaTig 200X. Any thoughts? It seems they get generally quite good reviews in the wild, and mixed reviews here.