Everybody gave good advice,especially Joe Steele and Alvin Linden. If it does happen to be a tap and you are not able to "worry" it out with a punch "un-screwing"it, then drill it out. This takes a solid carbide #31 drill
,set precisely over the broken tap in a drill jig. The broken tap has to be chipped off so that it is flat, to keep the drill from"walking"(this is also why the jig is necessary). Set the belts on the drill press,or turn the variable speed so the drill turns just as fast as you can turn it. Feed the drill very slowly, until it is cutting cleanly and not trying to walk any more. This will work with "high speed" taps that you may not be able punch out.
Mike