This seems to be the same selector type, found in a different type of equipent I slaughtered (Japan, about 1985).
I have no idea, if the plug is generic or individual to the unit, so the diagram might be OK - or not. I assume it's generic...
The plug is shown with the arrow pointing upwards (and from the back, of course).
Hope this helps, at least it matches your drawing (upper left is nc on my connector as well…)