Nuka was wondering in /septagon/ a while back, and I didn't notice the thread, if the search bar was broken.
It is, and Cheat said he has no plans to fix it.

There's a super simple workaround though.

Go to google, and precede your search with site:sep7agon.net

Here's an example

What if I'm looking for something more specific?

Well, if you know about when it happened, just add the month to your search, since post dates are listed on the page.

Even just specifying the year helps.
Be sure to list who posted it too.

Here's a more refined search.

The thread I was looking for moved up four spaces.

I hope this makes you less relient on Sep7's shitty searchbar.