"alan_m" wrote in message
...
One other trick that can work if the screw is tight is to put the
screwdriver on the screw head and then give the other end of the screw
driver a whack with a hammer. Often then it starts to undo.

I've never found that works for me with seized screws, though I've often
tried it on the grounds that this time might be the exception! The usual
problem is not with screws that are painted over, but ones which have seized
into swollen wood or where the head is so rusted that it disintegrates and
becomes a round hole (if it was previously cross-head) when you apply enough
force on the screwdriver (by hand or by electric motor).

I had to remove some hinges from a gatepost, and one screw out of the four
on one hinge would not budge: no matter what force I put on the screwdriver
to push it into the screw while trying to turn it, the screwdriver just
climbed out of the screw head. Drilling out the screw head was a dead loss:
in the case the screw was so hard that a metal-rated drill just got very hot
but made no impression. I ended up having to hacksaw through the hinge to
cut the moveable blade off the part that was firmly and immovably attached
to the post, and then use a burr tool to smooth off the sharp edge on the
cut end. Leaving the remains of the hinge, as long as it was not dangerously
sharp, was not a problem in this particular case.