The following lines were added (+) and removed (-):
The location of the discriminator audio which is pin #10 of IC #3, 3359DA. Pin #10 is on the top right corner of the chip. Solder to the lead to the resistor at TP3 which is connected directly to PIN #10 of the IC. You can put a 10K ohm resistor in series with a 10 μF tantalum capacitor. Connect the (-) ground wire to the chassis.