Tombstone maint question

I picked up a used Lincoln Tombtone a few years back, at a pawn shop. When I got it home, I simply hooked up an extension from my electric range and ran a short bead out in my yard. Just to see if it worked. It seemed to run okay. I never got a 220 outlet installed for it, until this month. And now when I tried it, ran okay, except that on two settings on DC it would not strike an arc. Otherwise it seemed to run good and stay constant. I kept trying all the settings (AC too) and it finally ended up arcing on all settings. So exercising the rotary selector must have cleaned the contacts. . . . . My question... should I leave the sleeping dog lie, or would spraying some TV tuner cleaner in on the rotary selector switch be okay? . . . . By the way, I nearly dropped when I saw an indentical new machine, at a local welding supply, for almost $600. I thought I overpaid for mine ($220). I only got it because I though it had a huge 240 v. extension. It turned out the pile of heavy cable was a 16 foot 220 v extension, and two 50 foot 600 amp leads... with the price of copper now, the leads would cost that much.