There’s a Google custom search in the header area above, however I found my ad blocker was keeping me from seeing it until I turned it off for this forum. Might not be what you’re experiencing, but just in case 🙂
I’ve just added a fallback site search which displays if the Google custom search fails to load. It will return the same results as the embedded custom search, but in a new tab which searches Google directly using the site:themeover.com search prefix to limit results to themeover pages.
I hope this system works for you. Please let me know if you encounter any difficulties.
P.S. I used the Ghostery Chrome extension to replicate your issue of not seeing the search form.