Quote Originally Posted by Doddy View Post
Are the motors energised? - can you rotate them by hand with power off, and with power on - start at the basics.
So, the answer is yes I could, so thanks for taking me right back there!
After a bunch more messing around, including checking with an old printer cable and hooking up some prototyping wires, I discovered:
a) It works through the LPT port
b) It then worked with the GPIO port
c) When I unplugged the printer cable it stopped working.

I can still turn the motors when they're energised, but they are more 'clunky' than when not energised and a bit harder to turn.

After even more messing around, I discovered that if you ground the appropriate LPT port pins to the same ground as the Pi, then the GPIO pins work!

I have a bunch more to fix, but it's mostly software related so I'm off over to the LinuxCNC forum. I just wanted to post this here in case anyone else has the same board, and thank everyone for their help!

Cheers,
Kev.