Product Sliders not visible.

Hi there, for some reason sliders are no longer visible to anyone visiting the site that isn't logged in?
Please visit: https://www.comicbookshop.co.nz/
There should be two sliders visible on the front page, let me know if you can see them.

Here's the error's I'm seeing in Google Chrome:

Uncaught TypeError: $(...).flexslider is not a function
at metaslider_53985 ((index):130)
at timer_metaslider_53985 ((index):148)
metaslider_53985 @ (index):130
timer_metaslider_53985 @ (index):148
setTimeout (async)
timer_metaslider_53985 @ (index):148
(anonymous) @ (index):150
(index):152 Uncaught TypeError: $(...).flexslider is not a function
at metaslider_50619 ((index):152)
at timer_metaslider_50619 ((index):170)