Yes, we had a couple of Aquapole with this issue, the top plug 1/4 inch screw coming loose. Only a couple of Aquapole are affected, and its an easy permanent fix when done according to instructions.
What you have done, putting it back in with super glue, was sort of the right thing to do, but super glue is not the right choice; it has to be 2-component epoxy glue or JB weld metal glue. We have a video on how to fix it here: https://www.youtube.com/watch?v=NSIZ7JWZS5g
If you encounter an issue with your Aquapole, please always reach out to customer service first before attempting any repairs.