The issue only surfaces if the sensor is plugged in, when the control panel is opened.
I presume this is because it is crashing when reading the sensor, and when it's not attached the circuit is returning something reasonable.
I'll be borrowing another controller soon, and in the meanwhile this one will have to be fixed properly.
In the meantime, I've been playing a lot with mid2cnc, playing pretty much anything I can find in midi format on the steppers. Flight of the bumblebee is a terrific test of printer speed. I ahev built up a pretty large library of midi files and their corresponding gcode, depending on whatever legality issues there might be I'll upload them. Also, I am fairly confident that I am the first to play Touhou theme songs on a 3D printer, but if I am not please let me know.
I've got a video of the machine playing, but I forgot to change the camera out of mirror mode, so I have to flip it horizontally.