The screen is blank or the graphics are distorted?
This is caused by dirty or damaged connectors in the game.You will need to clean the games on a regular basis to keep your NES working properly. Dip a Q-Tip in the cleaning solution (Windex or a solution of 50% isopropyl alcohol, 50% water) and rub firmly across the metal contacts in the bottom of the cartridge. Repeat until the Q-Tip comes out clean. Use a dry Q-Tip to wipe off excess solution. Once the game is dry, plug it back in and see if it plays, if not repeat the cleaning process again. You may also need to insert the games a certain way in order to get it to work. There are two things you can do to help. Place the game in the top of the system without pushing it down into the connector. Hit the top of the game with a fair amount of force to pop the game into the connector.