These are centered by means of the small nut that can be found within the black plastic cap on the front of the brake. Weinmann made a special tool for this which is going to be difficult if not impossible to find but a crescent wrench should do the trick. You can pop off the black plastic cap with a thin screwdriver. You can pop it back on when you are done. You may have to back off the nut that tightens the brake to the frame (found behind the fork in front for example) a bit to make the proper adjustment. There may also be some flats just behind the brakes that can be used to adjust them. If there are you will need a flat wrench to adjust them but I think the right adjustment is I have described it. In any case, take some more close up pics and put up a new post in the mechanics forum. You'll get some more info that way.