Well I guess it proves that wasn't the problem. B-)
I don't think graphite will help with a stuck pin you won't be able to get to where it's needed.
I don't know why everyone else was faffing baout taking covers off and removing headless bolts. Just take big screw driver and large hammer. Drive screwdriver into lock slot and twist. That's how some toe rag knicked one of my cars once after doing the same trick to the door lock...