I got a good deal on a vintage 500 amp Hobart. I was welding last week, and the amperage selector switch threw sparks when it wasn't under any load, then I had juice at the ground, none at my stinger. These old models have a polarity switch, and I'm sure it's the culprit. Just wondering if my damn rheostat is probably fried too. I wouldn't have juice at the ground if the rheostat is fried, right?

Tommy, you have an old Hobart.....you ever deal with this?