Response from Jonathan: According to the manual for the 60-in-1 board, none of the games require a 4th button. This is why they typically only have 2-3 buttons wired up. If you’re talking about building a 60-in-1 cocktail with 2 buttons for each player (4 buttons total) then you will need to wire these buttons to each player’s panel from their respective sides of the JAMMA harness (parts side for player 1 buttons, solder side for player 2 buttons). Hope that helps.