I recently purchased an Atari 2600 with the old RF switch included in the box. The Atari is in great condition, and I went to Radio Shack and purchased a 75 ohm RF switch. When I turn the console on, all I get on channel 3 is a black screen and a green screen on 2 and 4. What is wrong? This happens with all games of all types. What can I do to fix it?