So, just thought I'd give an update in case it helps others.
I managed to find a dealer not far from me, they had a cable in stock and were pretty helpful;
http://ikonikmoto.com.au
Cable changed but now it idles really high. With the choke closed it revs high on idle and the idle screw has no effect. Twisting the throttle seems to make it flood - the revs drop off and it struggles for power.
Unless someone has an easy fix or can advise on a course of action for diagnosis at this stage I think it's probably beyond my abilities to resolve so I'll be taking it to an expert later this week.
Thanks for the help folks