Yesterday, I was welding dirty angle using 6011 rod DCEP. At some point it occurred to me that I was using an AC capable welder so I switched the selector handle to AC and the arc power became weak and it was hard to maintain an arc. It would weld, but it acted like it needed the amps kicked up 30 or so. I had been using DC at 90 which was about right.

I seldom move the selector as I rarely weld aluminum. The selector has never crisply "clicked home" as I would like to see a switch of this type do. Some wiggle will make it happy at EP and at EN, but it seems to get lost looking for AC (which is the middle setting)

I need to open the case, blow it out & clean & set the points.

Any ideas relating to the problem? Tuner spray? Electrical contact lubricant? Working the switch back & forth to limber it up?

There is a lot of "slop" between the handle and switch shaft and it also feels like there may be some within the switch internally. Curiously, there is a "shear pin" sort of cotter key like pin which fastens the handle to the switch shaft that accounts for a lot of the looseness. If I didn't know better I'd say it was a shear pin. It may, in fact, be one as it seems that you could shear it with just a little effort. Almost even money tells me this is a protective mechanism. Does this have anything to do with anything? ---dumb question, I know but it's either this way for a purpose or really lousy engineering.

Any help or suggestions would be appreciated.