Ahh, the old broken extractor problem. The extractor metal is very hard and causes the drill bit to wander, ruining the hole.

Take it to the machinist. You need a drill press and a clamped work piece. The machinist will have to be careful not to ruin the taper at the bottom of the hole and also not get metal chips inside the caliper.

You've got nothing to lose at this point.

__________________
1981 300TD 310k miles
1970 280sel 172k miles
1966 230 Fintail 162k miles

"Where are we going? And why am I in this hand basket?"