Today I used dishwashing liquid and warm water to clean the screen...wiping horizontally. About half the shade of the dark areas comes off.
Very happy with the result as the lines in the screenshots are harder to notice now..but I can still see it. Wish I could totally clean the dark areas.
I don't have denatured alcohol to try but google said it's pretty much the same as methylated spirit which I tried in one corner of the screen but didn't notice any improvement.