Miller Thunderbolt 225 adjustment...

[Mr. Sunshine]

HI everyone, I picked up a Miller Thunderbolt 225 at a garage sale. The man who bought it tried to teach himself to weld, but lost interest. He set the welder aside in an open barn for twenty five years or so before I bought it. It has a big piece of metal that moves up and down through another big piece of metal to adjust the current. The two pieces were rusted together pretty solidly. I took the machine apart and soaked the pieces in PB Blaster for a few weeks before they came loose.
I put it all back together this morning and it welds nicely. The only part I’m not sure of are four black plastic blocks the adjust to keep the moving part centered in the other part. I wanted to see if anyone knows how tight those blocks need to be or if they need a small amount of clearance between then and the moving part.
Any help would be appreciated.

[Louie1961]

Its a judgement thing. Those are the shunt blocks. Too tight and it becomes difficult to adjust the amperage, Too loose and the box will buzz loudly. Find the balance between too tight to adjust and too loose (too noisy). Grease them up good with a white lithium grease or similar before tightening.

[Mr. Sunshine]

Thanks for your help. I greased it up and buttoned it all up again. Now I have a great welder for twenty five dollars.

[wayne55]

I have the Hobart Stickmate, same machine except for paint. I bought mine new and I was afraid I would break the plastic handle making adjustments because the shunt blocks were so tight. So I loosened each screw on the shunt blocks about an eighth of a turn or so.