Richard - It seams the wiring diagram that I have for v6 doesn't completely match the code (I'm guessing it's wiring for something between the v6c and the v7e setup) - the position switch I referenced (isn't the joystick) it's an 8 mode position switch for threading (I think) and it doesn't have code in v6 as it uses pins (22 to 29).?
I did find an answer on the encoder and like you said the LM293 is only needed for printer encoders - it also looks like the 7486 isn't needed anymore for v7 based on this:
