I used your schematic to do this mod on an Atari 2600 Jr. Since your guide was for a 4-switch model, I couldn't use the guide, but the schematic for the mod was perfect. I just so happened to have the necessary components in my component drawers. While I had the system open, I replaced the electrolytic capacitors on the board as well. This would be recommended for anyone doing mods or repairs to old consoles. They dry out and don't work as well. Here's a photo of it playing Dig Dug on my 50" TV.