Originally Posted by Brian Carlton

I'm quite sure that the "rotor" is the culprit. But, whether the rotor is "warped" due to the cast iron moving around or whether the rotor is "warped" due to accumulated pad deposits is the question.

How about this:

Put DTI on outside face of rotor. Observe runout and mark high spots.

Put DTI on inside face of rotor. Observe runout and mark low spots.

If amounts are just about identical and at the same positions, it confirms the rotor truly has a runout of the cast iron.

If the amounts differ and are not at the same angles, then the culprit of pad material accumulation on the surface begins to gain some credibility.