Removing Melville Clark Let-off Rail Brackets.

A method I have used with success on broken let-off screws with one
end still sticking out might be adapted here.  I turn the let-off rail
so that the let-off screw is horizontal, then with a match or torch
I heat the tip of the end sticking out red hot.

Remove the flame and turn the rail so that the hot end is down.  The
heat will travel up the screw and loosen the screw.  I grip the hot
end with a pair of Vise-Grip pliers and keep testing, turning back and
forth, until it turns.  If it is really hard I may have to heat it two
or three times.

John Dewey