Photo 1
The red Organ button when not activated (normal position) makes contact with the blue (arrow) wire to the Volume Pot (?)
Photo 2
When the red Organ button is pushed it makes contact with the red (arrow) wire that goes to the Tone Pot. at the same time, when activated it disconnects form the (blue arrow) wire to the Volume Pot.
Photo 3
Top (upside down) view of wiring. Showing where the red and blue wires are going.
I realize this is a poor explanation, and anyone with more expertize is welcome to scrutinize my evaluation here. I am only trying to show what I think is going on with the red Organ button.