Some tricks I sometimes try:
* If you happen to remember some piece of exact wording from anywhere in the question or answers, SE search is often pretty good for finding that (even if it has nothing to do with the subject of the question)
* Start asking the question over again; the little search there seems to use a different algorithm than the main site search, and sometimes I find what I'm looking for that way when the main search didn't turn it up.
* Search using google/your search engine of choice with "site:blender.stackexchange.com"