I bet in the end, you'll have to buy a new welder. I believe you should just go buy the Vulcan 215 or 220 and call it a day. There is a reason that part got fried.
Looks to me like that would be a TIP142 transistor. I'd make for damn sure you don't have any burnt traces on that PCB before you replace it though.
Whoops, I'm a day late and a dollar short... story of my life...It's a TIP 142. (npn)

It's a TIP 142. (npn)
There's a lot of TIPxx2 or TIPx2 parts that are NPN BJT, how do you know it's a 142?
If it is a TIP142, that's a $1.50 part and readily available online.
Well you were right, the 142 is the complementary to the 147.
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Can I please mail this board to you and pay you. Holy cow you and Braxton know your stuff, you guys are awesome.That's a very good point. I didn't think to look it up as the complement to the TIP147.
Outstanding work, everything points to that being a TIP142 from the other schematics. I'll have to poke around later today and make a shopping list for John if he wants to fix it or have it fixed.
Thank you Soo much for finding this stuff. You guys are a blessingWell you were right, the 142 is the complementary to the 147.
Plus, this. Century | Search Results | Joe The Welder
Fan works as it shouldIs the fan even coming on? It could be the fan motor locking up and humming.