Great job. Many years ago I tried to drill out a broken adjuster screw in a campy dropout, and the hole I drilled ended up quite a bit off center on the outlet side. Obviously, I couldn't figure out how to keep the bit parallel to the dropout face using a hand drill. I also did not use a high quality drill bit. I ended up not tapping the hole for a new adjuster screw and just used one of those clunky inserts. Afterwards I still rode the bike but I always worried about the dropout integrity. Even after reading about your success, I don't think I will attempt it again.