Threads that are moved get a temporary redirect for those who are following them, so if they are not where you last saw them, there should be a link in the old forum that usually lasts for about a week. After that, try the search engine.

If they get moved to the Soapbox, which includes the "Gloom and Doom" subforum (the likely destination of threads moved from the "Product Availability" forum), then they are subscriber-only, and they are shielded from search engines.