The Natural Philosopher gurgled happily, sounding
much like they were saying:

I would say there was lots of wear left on those pads. I can't quite
see, but lots of pads these days have thin metal projecting fingers
that rub on the disk when the pads are worn right down. They make a
screeching noise when they contact the disk. It just an audible
warning.

No that's the backing plates hitting the disks, a sign that you are
ruining the discs.

Not necessarily.

SOME cars USED to have copper wires embeded in the discs that lit a
light on the dash when they closed the circuit to the discs. Always
either corroding to a short, or wires falling off so they didn't work at
all. Not seem them recently.

That's because they've largely been replaced by the audible warning harry
describes - since the wiring to the pad wear sensors is always in a right
old state.