This specimen is so dark that I originally thought it must be Y. hunterorum (also known from the ACT, but not yet recorded for Canberra Nature Map). However, the hind wing plaga is not white enough for hunterorum. So I have now confirmed your ID (to genus), Ian. I can't confirm the ID to species level at this stage. Most interesting.
I have some more images which I'll post shortly, but given Yoyetta spp. to the uninitiated like me are difficult to see and photograph, I can't guarantee they will add to the story. Is there some sort of vernacular 'key' to the Yoyetta g. available? (i.e in addition to your excellent website, of course).
Did you try to enhance the third image to get a better view? I had a look in Photoshop and seemed to see two red dots between the eyes(?) as in your image of Y. hunterorum on your website, Whether that could be diagnostic of that species, I'm not sure.
The red dots that you describe would be the ocelli (simple eyes), a feature present in all cicadas. Taxonomically, the genus Yoyetta is a work in progress. Preliminary keys have been produced, but these aren't currently readily accessible for the uninitiated. Work is currently focused on getting species described, but there is a lot of ground to cover in this genus. I suspect this is most likely a particularly dark individual of Clicking Ambertail. A taxonomic description of that species is in preparation (a collaborative study).