It's true that Tecumseh engine manufacture was shut down in 2008, and they no longer supply parts.
But many bits for the later model engines are still available in the US.

There are two awkward things about that situation:
1. Many US retailers won't accept international orders at all. Something else to watch out for, is will they accept non-US credit cards, or PayPal - other methods of funds transfer are exy [e.g. Western Union].
2. When you find one that will, postage can be a bit exy, even when they will use USPS [the US Post Office]. I say postage here, because couriers like FedEx, UPS, DHL are to be avoided, due to cost.

Duty/GST at the Oz end isn't a problem, so long as the order is under AU$1000, at this time.

A couple that will accept international orders [no personal experience with these; just as examples]
http://www.jackssmallengines.com

http://www.ereplacementparts.com/ - this mob ship through a third party forwarder

Cheers,
Gadge

"ODK Mods can explain it to you, but they can't understand it for you..."

"Crazy can be medicated, ignorance can be educated - but there is no cure for stupid..."