The plastic bushings on the Mafacs could be replaced easily. Hardware stores have bushings, but the right size might be harder to find. I've been thinking of machining the bushings - and they are bronze, not brass, as far as I know (and so are the ones in the hardware store). I haven't got around to it. Anybody interested? I can provide specs.
HOWEVER, the brakes work great even with plastic bushings, so I haven't felt the need. Consider than the bearing surface on the large pivots is much greater than the pivot bolt on a standard sidepull (such as Campy NR), and even those don't seem to be a problem.
Jan Heine, Seattle