Re brakes
You should also check that the metal that you are sticking the brake pads to are flat mine where not as they are only punched out in the first place.
Put them in a vice and make sure thet are flat then glue on the brake pads and put them back in the vise and tighten while the glue dries. Then sanding is minor.
But scince have gone to teflon brake pads and the 1 piece brake disc off the mrx3 .
It is the way to go