I am trying to remove the flipper to replace it but I can't undo the screw that hold the shaft, as seen in the pic.

2019-06-01 18.59.29 - Copy.jpg

I have sprayed WD40 on it during the day but it still won't budge.
I have also used a nail punch and hit it with a hammer, shock attack, no good.

I have heard of the left hand drill extractor bit, do they work ?
Any advice on how to remove them would be great.

btw, this is on a Gottlieb System 1 playfield.