You could check by identifying an axis direction pin, then connecting a voltmeter, jogging that axis in one direction should show (approx.) 5 Volts and jogging in the other direction should show (approx.) 0 Volts.
If the maximum voltage shown is only 3.3 Volts then you could perhaps consider fitting your PC with a PCI Parallel Port card which has 5 Volt TTL output.
Tweakie.