Interesting Ken, I'm not sure about your friend's brakeset, but newer (1980-ish) Weinmann sidepulls began to come with improved pivot bolts - the front ends terminated with a hex-shaped front which could be grabbed with a thin (6mm?) socket tool. This simplified setting them up initially and allowed you to tighten down the lock nuts for the pivot bolt VERY securely while holding the bolt stable, and then attaching the black plastic outer cover kept the nuts from loosening - the standard (new) set-up for Weinmann's best brakes at that time. My 605s even have plastic lined... uh,... "nibs" where the tension springs contact the arms - to minimize drag as the spring slides along those points. This was much like the idea behind the inserts on the later shimano BR-7400 (and ultimately the full sleeves that the BR-7402s finally got a few years after that). I do wish Campy had come up with that for my later NR and SR calipers... But really, so long as those contact points are kept lubed and grit free, any brakes should continue to tighten evenly. The 605s did come stock with those same very basic "WX" style pad/holder units that their old center-pulls and every single other Weinmann brakeset came with well into the 80s. I replaced those with some Scott-Mathauser red pads. [Those always improve any brakes and some may still even be available from Rivendell.] I'm also using new Aero levers on the ones I've mounted (adds another little bit of boost).
Personally, since they're probably not original on that bike anyway, I'd just replace them with some decent modern dual pivots like the Shimano BR-R600, Cane Creeks, or (best bargain of all, around $20-25/ pair) Tektro's 521AG - all of which are longer reach calipers (up to 57mm.) and are far more effective brakes.
Bob Hanson, Albuquerque, New Mexico, USA