dc42:
The wiring of the pot in the photo looks correct to me, assuming it is a normal pot with the wiper being the middle connection.
Ok I'm blind, I magnified it and now I can see that the orange wiper wire extends beyond the power bus and into A1. What about the red wire on the outer tab of the pot? It "appears" to be connected to an empty bus strip I think. Also I see a ground wire connecting the bottom negative bus to the top one, but I don't see a positive wire extending to the bottom bus.