It sounds like the input for the back gear switch is backwards. Look at the input screens to see which input is changing when you flip the switch back-and-forth. A zero is off and a 1 is on.
Is this machine a Partner 3 or a Partner O3, they made both. The P3 is a heavier casting with a fixed head and a quill, the O3 has the mill-slide with a regular knee-mill head. I can get you the drawings of the O3 head if you can use them.