I have a question about setting these up, before I transfer them to another bike. These are circa 1979 Suntour Superbe side-pull brakes. They look great, but on the old bike, they always seemed to pull themselves off center a bit and rub the rim after a bit of use.

Is this a common problem, or an issue with the way they are installed? What is the fix, or is there one? thanks

p.s. I am not vintage-savvy, so don't assume I have a starting knowledge base; I won't be offended if you dumb it down.