Well got the part in today and made an appointment at the garage tomorrow to have them replace it. Discussed the problem with them over the phone and they made the same guess before I even mentioned already having the part in hand. They're going to replace it tomorrow and box up the old one for me, in addition to checking fluid levels and anything else that might have gone wrong. Once I get the current switch out I'll compare it to the "dirty" switch pics in the other thread to see if maybe it can just be cleaned. If so I'll list it here for anyone who's interested.