Can you measure the physical size of the existing resistors? i think you're probably after 10-20watt ones which are 30-50mm long and about 10-12mm thick, but i don't know the machine itself so i'd need to see them....
IF that's the case, is there an electronics surplus shop near you, or search ebay or electronics-surplus stores online.
(these are waaaya beyond the level of Altronics or Jaycar, in fact someone like "Oatley electronics (nsw) may also be worth a try.
Here in VIC we have Rockby electronics which may have them too....
The large power resistors can be associated with power supplies, audio amps, ham-radio etc etc, so you find them 'somewhere' that has them easily for you....
