When you say you've "lubed the pots", what did you use for that?
I'd recommend that you go out and buy yourself a can of Servisol (or other brand of electrical contact cleaner), and spray not only the selector switch, but the pots as well (into the little square "cut out" on the tab side of the pots). When you've sprayed the contact cleaner, make sure to "work it in", for the switch, spray the cleaner on, waggle the switch around a few times, spray a bit more, waggle again, for the pots, spray some in, roll the pots back & forth, spray a bit more, roll back & forth again, etc.
I used to have a Gibson LP that would regularly stop working or go crackly for no reason until it had been given a good squirt of Servisol.