I’m not sure how to strip the clamp but I’m going to have a look at it either way.
Sorry, after re-reading my last post, I need to clarify. The threads on his quick release jaw were stripped enough to cause the threads to slip under load. I wedged a piece of wood into the “cage” in which the jaw was housed to keep in the locked position. The vice now works again, but has no quick release functionality. It can be used as a backup/secondary vice.
His vice’s jaws had a nice feature, in that the threads in the jaw can be replaced. They were designed to fail before the main screw (softer metal). Unfortunately for him, though his vice was only about 5 years old, the manufacturer went out of business and parts could not be found.