Common sense and eye-protection is part of the deal.
The hardness of a small file is exactly what's needed IMHO when dealing with a hardened pin.
Ordinary chisels are hardened but not to the same degree as files. The edge of a small file has a chance to bite into the edge of the pin.
To minimize damage to the crank, a careful approach is needed for sure but to have any effect on the pin, a harder tool or drill is needed. I can visualize a home-made tool to try and loosen the broken pin but it's not easy to describe it.
Failing that, I'd sacrifice the old pulley, install it and use it as a jig for drilling the broken pin out.
I am only an old dude with decades of hands-on experience in dealing with machinery.
Better brains are out there with a solution.
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1980 Carrerarized SC with SS 3.2, LSD & Extras. SOLD!
1995 seafoam-green 993 C2, LSD, Sport seats.
Abstract Darwin Ipso Facto: "Life is evolutionary random and has no meaning as evidenced by 7 Billion paranoid talking monkeys with super-inflated egos and matching vanity worshipping illusionary Gods and Saviors ".
