New brake guide pins are called for when servicing rear brakes on 100k mile +, first generation MINIs. The bad news is these stainless steel guide pins list for more than $20 each. Indeed my guide pins had surface pitting and rubber transferred from the guide bushings, but they were still straight, and I don't see these requiring a precision fit. I polished them with 2000 grit sandpaper to give them close to a new finish. New guide bushings went on the calipers plus a little high temp synthetic/PTFE grease for the guide pins. Replacement clips were installed too, although I don't think there was anything wrong with the old ones. The piston boots and seals were still doing their job, and I've discovered over time some things are better left untouched.