Good evening David and welcome to the Events Calendar Support forum!
Thank you for reaching out to us.
I would love to help you with this topic.
You could tweak and apply the following snippet in the functions.php file of your theme (without the PHP tag at the top): https://gist.github.com/andrasguseo/b8e2739b11fdbd2d5ebacce23d862046#file-ical-export-events-custom-php
But first to be extra safe, before making any changes to your functions.php file, you should make a backup of that file.
Let me know if that helps.
Have a great day!
Geoff B.