At some point recently our site stopped returning results for searches of product by part number. So far I've reindexed, I've tried all the different search modes, we've removed all disabled products (I heard there's a bug in the disabled products code that can cause whole categories to disappear from search), I've even disabled the extension that was updated recently. I've flushed the caches after each change just to make sure. Still no luck.
Searches for part numbers come up with "Your search returns no results." Searches for some other terms that are in part descriptions will find some, but not all the items with those terms in the description.
I'm not sure how to proceed from here. Ideas?
Perhaps a better question is: "How does Magento search function?". What are the dependencies/expectations for an item to be found via search?