Plugin Events Manager postcode (zipcode) search

I want to add a postcode (zipcode) search into Events Manager. I found this one started by melon503 6 months ago marked as resolved, but I can’t get it to work. I added a question but no-one has responded presumably because it’s marked resolved. So trying again with my original question in the previous post as a new one:

“I’m a complete beginner at PHP and am stuck.

I’ve loaded em-events.php into a php editor, found line 231, added the code above (with a change to match Google Maps API 3 as below) immediately after it, but no postcode box shows on the Events page where all the search parameters are.

My revised API line is:
$base_url = "http://maps.googleapis.com/maps/api/geocode/xml?address";

Could someone please let me know what I’m doing wrong?

I’m expecting to see an input box for postcode and radius in the search page – is that right please?

It would also help me if someone who has it working could post the actual line 231 referenced, just in case the editor I’ve used is doing something different.

Thanks in advance!