If you look at the top of the board, at the plastic connector that houses the wires that lead to the pot, you will see letters designating the wires' function: V + R L G L R
The G is ground and should connect to both left and right grounds on your new pot or to RCA jacks. The R L, between the G and + go to the left and right positive inputs on the jacks. At this point, L R are no longer used. V + go to the power switch.