Bushwalk Australia

Just in case anybody here knows off-hand what the thread happens to be in the kerosine jet
and if it has changed as my old jets don't seem to fit the new stove
MSR haven't replied as yet

Which stove are you having trouble with? To be honest I have no clue on the thread size, but maybe try these guys who are the distributors of MSR gear in Australia: http://www.spelean.com.au/welcome.html. I've had to contact them in the past for a spare part for my Dragonfly and they were awesome, really friendly, helpful, and sent out what I needed at no charge.

Another suggestion would be to see if you can find an old Expedition Maintenance Kit for your stove. I know most have spare jets with them, so you could find a replacement for your stove that way too.