I use HN Search, which is linked from the bottom of most HN pages. That's definitely a text indexing tool that helps! The search company Algolia provides it for free—a major service to this community, because not only does it help users find things, we rely on it heavily for all kinds of moderation tasks.
It's particularly helpful to include "comments > N" or "points > N" if looking for old threads.
It's particularly helpful to include "comments > N" or "points > N" if looking for old threads.