ok so the pads were easy enough. i noticed however that the pad that had the spring missing has a notch worn out of it by the disc.
on the other side of the disc, the worn ridge was right at the lip of the disc, on the side with the wobbly pad, the disc was worn about 5mm into the surface of the disc to match the notch on the pad.
not sure if this was caused by the spring coming off and allowing the pad to move about. im guessing the new pad will have a notch worn into it as well rather than wear the disc down evenly.
i'm gonna have to change the damn disc aren't i