Ummmm, don't these things almost always have a Zener on the output ?

That would have had to gone open. Usually I see them dead shorted if they get overloaded. That's because the pass transistor is shorted which made the Zener short, which means it is shorted all the way around.

Of course on any given Thursday run there could be some units that have an open Zener. And you'll never know it unless the rest of it fails.

Just love this business.