We've got a deadbolt that decided to stop working today. When we turn with either the key (outside) or the lever (inside), the deadbolt moves about 1/2", but no more. It does not retract all the way inside the door, and therefore we can't get the door open.
It's not jammed or frozen, as the movement seems fluid, just not far enough. What would cause this, and how might I go about fixing it?