I have an unusual issue with my Atari 2600. It powers up and shows the game fine. I can go through and select the various games for the cartridge but when I hit the switch to play, it changes to the proper color but doesn't play. For example, in Space Invaders, on the select screen I can actually move the ship with the controller and the aliens move but when I hit the switch to play the game, nothing moves. Anyone have any idea what's going on? Thanks in advance.