Cleaning the screen is simple and striaght forward when done properly. Worst-case is scratching the screen and/or damaging the bracket that holds the screen. Do not use any liquid. Learn how to properly remove the screen. Preferable to use the Nikon tweezers to release the bracket and hold the screen. Use a RocketBlower or equivalent to blow dust/debris. Consider holding the screen with two fingers by opposite corners as a Blower can quite easily dislodge the screen from tweezers. Blow upward so as not to launch more debris while holding screen close to a soft surface in case of drop. If debris persists, use a proper brush, Pec Pad or equivalent to extremely gently dab the offending bits of debris. Use a fraction of a fraction of the pressure you might otherwise use to dab debris from your cornea. Do not use any liquid. Do not 'brush' across the entire surface unless absolutely necessary. The aim is to oh-so-softly dab and lift. Use the brightest light you can find and a magnifier to examine. While screen is out, Rocket Blow the mirror box. Ensure that screen is properly seated in bracket before returning bracket to 'locked' position.