Fives-Cincinnati (800-934-0735) is still the official support for these machines, and they usually have the cables in stock, although they may require you purchase a harness assembly with x and y axes together whether you need them all or not. I believe Mike Kilroy Corp can also make you just the cable you need, but likely will have to make it to order so won't be quite as quick as Cincinnati.
That said, why do you think it is cable, and which cable do you think it is? They are known to fail, so is a good possibility but there are many other items that will cause that issue. Could be as simple as OT switch stuck on too though.