Reply To: Broken Thumb Screw Removal

[Sam M.]

I would almost be tempted to drill a hole in it, tap it, and insert a strong (grade 8?) bolt or rod that you can put a lot of leverage on.  Then, after a lot of soaking with penetrant, try to twist it out.  If the penetrant has not seeped through the threads from one side to the other, put more on until it seeps through before trying to twist it out.  That would be my suggestion.