Thank you for the details, they worked flawlessly.
The good news is, that I was able to track down the code that is responsible to print the header form, and was able to make a change to it so now the ajax search pro shortcode is displayed instead of the default search bar.
The bad news is that it was not hard-coded into the theme, but included from one of the plugins called hybrid-composer. I guess that might be bundled with the theme or something similar. Unfortunately I had to make direct changes to one of the plugin files, as the search form was simply hard-coded there. In case that hybrid-composer plugin is updated, this change will most likely be deleted.
In that case if you need to restore it on an update event, just follow these steps:
– Open up the \wp-content\plugins\hybrid-composer\headers\menu-classic.php file via FTP
– Replace it's contents with this: https://goo.gl/Gboqe7
And that should restore the changes.
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