Haha! I just replaced my ignition switch yesterday.
I can't help with your question, though. Sorry...
I did find the cause of the failures. Some of them, anyway. The clock spring rubs on one of the position lock tumblers and eventually wears a divot into it, causing it to hang up or not rest in the correct position, throwing the contacts off or causing intermittent contact.
The contacts themselves looked new.
EDIT: according to the interweb, your assumption is correct on the white switch.