Cogging happens when the ESC can't find the position of the rotor inside the stator. Naturally it can't because it's not sensored. Has absolutely 0 to do with replacing slipper pads. BLX ESC's don't offer timing settings, unfortunately, you are stuck with factory timing too. The best way to get rid of cogging on a factory ESC is to gear it properly, set the punch higher or at the highest it goes and make sure there is no binding anywhere in the drive train. High punch means lighter trigger finger till you get used to it.