I believe you are slightly misreading the model number 108902. When I up the type number it shows a 100902-0245-99 (trim codes before 1983 are all now combined under 99). The date code indicates it is a 1968 manufactured October 09.
The carburetor repair parts needed are still readily available here and should still be in Queensland too.
Carburetor to tank gasket is 270073 and the diaphragm pump gasket is 270026. You also may need the pickup tube(s) if they have broken off. PN 391813 for 2 and 3 quart tanks and/or 296811 (superseded to 497413S). The carburetor itself is no longer available.
