I've read your posts carefully, but I'm not sure I understand what you're saying. If the frame has a cable stop, then the housing's ferrule rests in the cable stop. You seem to be saying that the "floor" of the cable stop has broken, so the ferrule is now inside your frame's downtube. But that doesn't make much sense, because it certainly wouldn't shift properly like that. In fact, it probably wouldn't shift at all. Can you take some close-up photos of the problem so we can see what's happening?