Given the 'zapping' I would be checking you do have a good earth. The normal easy test is one of those plugin testers with LEDs on, but given you're down under, I'm not sure what would be available. It's also worth running the machine at the same time as having the tester plugged into the next nearest socket, just to make sure a good earth remains with things under load.

If you don't have a good earth, then the various filtering capacitors typically found in mains connected electronics (VFDs especially), can cause a voltage build up, which will earth through the nearest thing, which can be the person in contact.
You may need to install a new earth rod, or figure out why you've got a poor earth.
(does Australian power use L,N+E, or a centre tap L,L,N/E? to get 110V and 220V?)