Cut the 8 traces directly above connector pins 6-13 on the backside of the board.

Add 8 resistors (100 ohms) between the connector pins and the sip directly above. You can also use a DIP isolated resistor network such as Digikey part #4116R-1-101LF-ND. The resistor value is variable (120 ohm will work), but too high will just display a red screen or other problems.

Do not let solder get far down the connector pin or it will interfere with the connection to the NES. Sometimes you can see scratches on the connector that show how much is used.

Cut out a notch in the back plastics for the new resistors