Great advice on the calipre expander but a g-clamp if used slow is just as good.
Consider taking off the entire calipre and replace the rubbers with a kit.
You need only the same spanners as for changing the pads, if I remember correct a 14 and 17 mm, spreader or g clamp, wire bruch to clean the slides a tub of white spirit to clean everything, a little grease for the slides and a little time.
Not just new pads, new brakes.