(T) front brake sqeel

hi had ordered some ebc green stuff pads to fit front and back and decided today was the day to fit fronts.stripped down n/s in no time and gave calliper a bit of a scrub with alloy wheel foam spry n a stiff brush and gently hosed clean.one or two crack looking lines on outside face of disc so checked otherside and found this.
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looked like totaly worn but found it was a build up of either pad material or brake dust.
these im guessing are original pads at 16000 miles and theres loads of life left in them.
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so job came to an end.scratched off as much as i could from disc with a sharp chisel, man its hard crap.didnt want to but ended up using angle grinder to get last bits off.once reasonable flat pad was sorted with a rasp/file slowly until groove gone.wont recommend any of this but needed to use car and was no good putting it back together as it was.
taken for a drive down quiet lane to bed original pads back in and all seems o.k.feels to roll and pick up faster so suspect brakes were binding on that crap.brakes easily as good as before so will shop arround now for some discs.