Update:
I cleaned everything... found a lead a bit like an old IDE hard drive lead that was partly unplugged, so I replugged it on the motherboard.
Swapped out three stepper motors - no difference - all behave weirdly when plugged into the & axis servo plug/lead.
I connected in the rotary attachment- it works fine - but it knows it's a rotary, although that does go in place of the flat Y axis.
I even reflashed the firmware, and removed and reseated the single RAM chip - still no improvement.
This is all while not connected to the PC - just in the booting-up, initialising & homing options, which does not need a PC to be done.
That eliminated the software and the LPT lead as a culprit.
What's weird is it all worked fine, then it suddenly did not.
I'm running it from Win XP, though the former owner was using Win7.
Any ideas would be appreciated!