I thought jamb was just the name of part of a door, so I looked it up. My dictionary seems to say that jamb (v.i.) means "to become unworkable, as through the wedging or displacement of a part", but jam (v.i.) could mean jamb or it could also mean "to become stuck, wedged, fixed, blocked, etc."Yes. Stuck or jambed (or just obstreperous.)
Is a jambed lock really more permanent than a merely jammed one?