Why do you think the flyback is failing?
It makes a bit of a zap noise whenever the tube starts.
I'll seemingly have to take the computer apart to fix this mess though
Mine does strange zap noise too. Really do not know if this is ok or no … listen for your selfIt makes a bit of a zap noise whenever the tube starts. I don't know if that's normal or not but usually it's not as pronounced on any other CRT I've worked with.
eMacs make a loud "DONK" noise, iMacs sound more like a typical CRT, this sounds like it's screeching for a second.