That 7th hole, on one side you put a spinner and on the other side you put the button that changes the joysticks from 4 way to 8 way mode. You leave the trackball because Teknoparrot now supports Golden Tee 2016 and it is amazing.
or
I used 1/4" plywood to transform a metal control panel, not sure I would really recommend it, but it certainly solved the problem.
-Zeosstud