Hi Ted,
Is there any possibility of using something to cut a notch for a flathead screwdriver? If not, you can get sets of bits for removing these screws. I have a set I bought at aldi years ago that I have used with success a number of times. It is called, quite surprisingly, a 'damaged screw remover set'.
I think there are some of these at Bunnings too.
Last edited by Sapper; 23/02/20 10:04 AM.