Correct - the legs of the wire spring can be bent (carefully) to change how the caliper sits when "open". Before bending, be sure the caliper is set up properly and that it is oiled. Make sure the centering collar (the shaped piece that rides on the fork) is centered and is the correct part for your style of fork (e.g., you're not using a Rudge contour collar on a Raleigh fork).
The Raleigh pattern collar has a cut-away to accommodate the shape of the Raleigh fork. Be sure there is light oil in the pivot point and along any points where the arms of the caliper contact each other.
Be sure that the blue paint on there has not gunked up any contact points.
Check the brake bolt tension - if it is too tight, the caliper will bind. Bolt tension is done by feel - too loose and the caliper wiggles and flexes, too tight and it binds and will not release freely.If you've ruled out the caliper position and friction/binding as the causes of the problem, then gently bend the spring as suggested. Be sure that the wheel is properly center and tightened down before bending - you don't want to bias the spring because it turns out the wheel is off-center in the fork when you do this work.
For the standard cable (not the double-ended/fixed length cable system), adjustment of the cable is set so that the wear adjuster barrel (the long threaded thing that holds the end of the cable housing) is set with fresh pads relatively near its starting position rather than the end or in the middle. As the brake pads wear, you want to adjust the barrel so that the pads move closer to the rim to make up for the pad wear. I usually set my cable with the barrel just a turn or so off the starting position.
It is common that even after all this, one arm has a little more movement than the other. What is important is that both arms apply braking force to the rim, and then release enough to let the wheel turn freely. If one moves a little more than the other but they both otherwise work OK, then I'd leave it alone at that point. Even when all this is done, expect only average stopping power in dry conditions. These calipers are anemic by today's standards, but are correct for the bikes.
