Raleigh steel caliper brakes are not that great. As stated take it off. I would unhook the springs and adjust the caliper so that it moved without friction and is not loose. then rebook the springs. Mount it on the bike. Reduce the cable adjuster to near minimum. adjust the cable and secure. If the caliper is too open then use the cable housing adjuster to get you to a good place. Mark the top of the brake mounting base (where the spring is trapped at the bolt) and tighten the brake fixing nut.There are a few ways to "center" the brake, by having a mark you can tell where you are and where you want to go. Tapping with a drift on one side of the caliper return spring can get you there, but you need a deft hand.