I'm ultra picky with windscreens. The best thing you can do, if get a stanley knife blade, drench the windscreen with soapy water and with the blade at a 30 degree angle to the screen, gently push it over the screen, with little pressure. You'll hear a grit like noise at first, but with a few goes over the same area, the noise will go and you'll have a very clean screen. A quick once over with a screen cleaner and it'll be a very clean screen!!!