> assume I have to remove the 3.5mm
> jack screws on the top of the casing What's the proper tool to do so

The hex nuts Nina made a tool just for that if anyone's interested: https://twitter.com/nr2097/status/565815987178831872 You can 3D print that to get a handy little device to screw in hex nuts with, without scratching the faceplate.

All the best,
Zoë.