Over winter I’ve taken the rear brakes apart to try and fix what looked like a lazy calliper. The inside of the left brake disc had evidence of only partial contact of the brake pad to the disc, as the shiny part of the disc was narrower than the right side. The rest of the inside of the disc was corroded, where the pad wasn’t sweeping the surface. I took the callipers off, and on the bench I took out the pistons to check for corrosion, cleaned the sliders and reassembled them with special grease for the pin sliders, and piston /pad interface. However, following reassembly with new discs, the witness marks on the new disc after a quick shake down, again suggest exactly the same problem is still occurring. What should I be looking at next? New pads? Refurbished callipers? Or do they look ok and I should just keep an eye on them? Old disc inside edge New disc witness mark with pads, showing similar pattern with reduced contact of pads possibly apparent. Other side of new disc for comparison.