While changing cables, I mistakenly loosened the downtube barrel adjuster too much. This caused the spring to eject the screw that attaches the barrel to the mount. As we all know, once something that small hits the basement floor, it might as well have been sucked into a black hole. I can't seem to find an exploded view of the adjuster anywhere. Anyone have one so I can determine what parts I'm missing? Are these parts readily replaceable, or do I have to buy a new one?

It's one of these: