Bleeder extraction

[Kneale Brownson]

Anyone got a sure-fire means of extracting a broken-off bleeder from the
front caliper of my wife's 4kq campmobile?  I tried my smallest
reverse-drill-extractor combination tool and it didn't do the trick.  

I have all the rubber bits out, so could I heat the casting to a nice red
color with my torch and then try the little extractor tool again? 

Threads on the replacement bleeder I have are 7 mm X 1.0.   I have a tap
that size.  Supposedly I need a 6 mm drill bit.  That I don't have.  Don't
know what the equivalent number bit number would be?????