I have acquired some vintage bicycles and in the process of cleaning them, have completely disassembled the center-pull brake assemblies. I did this twice, once with Weinmann 999's and once with Dia-Compe's. This produced some brilliantly shiny brake components, but when I put the brakes back together, they function, but they are not "right".
The springs that hold the brakes need to wrap around the pivot bolts one more revolution than I possess the muscle power to achieve (even using the crude tools I have available to me). I presume there is some tool or some "trick" that people use to do this.
If someone out there knows how this can be done, I'd like to hear it. I have been able to find replacement brakes, but I'd like to make these other two sets that I have "usable" again.