I always have a can of brake cleaner handy.
Spray onto a rag & then wipe rotor thoroughly.
If there is still no bite I remove the pads, spray brake cleaner onto some 120 grit sand paper & gently rub the pad face in circles in the pool of cleaner to get 'em back to new material.
Then go do a good bed-in run down the hill to re-deposit fresh pad material.
For some reason I had a rotor/pad combo that would often glaze (or get oily) & I would have to do the above process every few months. Since I chucked the pads for new ones it's been OK.
I wonder if sintered/metal are better or worse for collecting unwanted residues....?
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