Originally Posted by
cny-bikeman
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.
Yes; the Weinmann "Symmetric" was one of the first dual-pivot brakes on the market, but unlike modern dual-pivot brakes it doesn't have that handy caliper centering bolt so you need to center it using the mounting bolt as described above.