as per title, would like to change the cylinder lock in a UPVC door for a relative that has recently moved into a new property and the retaining screw isn't budging! I'm in real danger of rounding the head if I attempt anything further. I tried WD40 but in reality there's no space for it to penetrate. not sure if the screw is brass but it doesn't seem to be that tough in terms of the head retaining its crosshead shape, I can't therefore REALLY go for it as I'm 99% sure it'll just round off.
is there anything else I can do that will make this stubborn screw budge more easily? please don't say all I can do is drill it out
is there anything else I can do that will make this stubborn screw budge more easily? please don't say all I can do is drill it out