Buckeyefarmer:
I have a 30 plus year old 180amp tombstone that had exactly the same problem. Switch was really sticky to turn, in fact all but froze up.
I took it the cover off and checked the switch. A little WD40, and patience working the switch and the contacts but particularly the shaft. The switch uses plastic moving parts and they get gummed up over the years. It causes excesive wear.
The WD40 cleans the gum away, make sure to clean it off the contacts after you spray.
I've been in the electronics business for 40 plus years. Fixed everything from big electrical contactors and motors to microwave gear, so I'm not intimiadated by anything electrical.
As far as a permanent fix, the switch will disassemble so you can replace the worn parts causing you the problem. You won't have to rewire a new switch. The only down side is that you won't be able to get the parts you need separately, you'll have to buy a new switch.
Sorry I didn't take any pictures when I did this, I was needing the welder for a project and was in a bit of a hurry. Just remember this ain't rocket science.
Hope this helps, take pictures so others can see as well.
Cheers.
Glenn.