@wolfwoman I would carefully drill a small hole straight down into the head, and send an extractor bit into that hole.
OR, use a bit the size of the screw head to just erase that head. More risk.
@wolfwoman it is careful work for sure. Steady, slow rpm is the way.
@b4cks4w Thanks for the ideas! I wish I had my dad's old Yankee drill. Power drills seem too powerful for such a delicate job!