Actually you are both incorrect as to how to center that caliper, although lubrication is a good first step. The OP has a very rare Weinmann Symmetric brake (ironic name considering the problem). See the 4th pic at this link for closeups of the construction. It's been at least 20 years since I worked on one but I believe you just need to loosent the binder bolt, clamp down the brake with the lever and retighten. Alternatively just loosen the bolt slightly and shift the caliper by hand until the arms come back evenly.