Happy to give back!

That's a really good idea about using a soldering iron. Currently, the ball plunger needs a bit of force to push in and then I put a dab of super glue at the bottom to hopefully help retain it. The good news is, even if the ball plunger falls out the charging block itself is still completely functional.

Another idea would be to use these grub screw things: Link

An advantage to those is you could set how easy or hard the retention is by how far you screw it in.

I'd just open up a hole from the other side of the block and thread it directly into the plastic. A dab of threadlock and it should be rock solid at that point. I've got some of those on order and will probably provide another file that utilizes them soon.