Cut a 11-1/2" lenght of shielded twisted pair. Prep the cable 3/4' at one end and retain the drain wire.
Prep the cable 1/2" at the other end and clip the drain wire. Strip back both ends of the black and red wires 1/4".

Using the 3/4" end, attach the black wire to the upper terminal of the poetentiometer that is nearest the power switch and solder.

Attach the red wire of the 3/4" end to the upper terminal of the poetentiometer that is nearest the heaphone jack and solder.

Twist the two drain wires together and solder, making sure they do not contact any other parts. Trim the wires back to about 3/16".