wrote:

Unfortunately, bicycle repair shops, unaware of the cause, use hammers
and punches to bend the offending spring

That technique was appropriate for some older sidepulls, models dating
from the early '70s and older, and was the only way to regulate the
centering of the caliper.

I don't believe it was ever appropriate. The anchor bolt on those
brakes could be rotated and the springs lubricated just the same as on
later more expensive brakes.

I had a Raleigh 3-speed with steel-caliper sidepull brakes.
The front brake bolt had a cylindrical concave surface that
mated with a convex surface on the fork. The bolt's rotation
was not adjustable. If lubrication didn't fix the centering,
the only other option I knew of was to bend the spring.

Tom Ace