[FLOORED]

Pretty much all of the above could be the cause of this. I have had mechanics look at bushes and say there fine but customers replace them and the problem is solved.
One thing i would like to say is that when you machined the rotors and the problem went away it did come back, now yes it could be resin deposits but it could still be bearing hubs or something else and i will explain why.
When you machine a rotor you true it up but if the cause of the issue is still there ie bearing hubs OR even pad rubbing etc it will come back.What happens over a period of time of driving is basically a flat spot wears onto the rotor and after a few thousand km's this turns into a judder as it is uneven when the brakes are applied.