Passenger Power Lock not working consistent

[limetwist]

I have a 2000 Ranger, and neither the fob or the interior unlock button will consistently open the passenger door. It clicks like it should unlock, but less and less is it actually unlocking the door.

I hope someone can help me, I don't even know where to start :-(

-L

...and I've been teasing my friend for years that he's a schmuck to have gotten manual locks and windows on his Focus, argh!