Thought I would post some pictures as this was an interesting repair to upgrade the bad 5V board to the 3V. The 5V board is upside down and has to fit between the metal wire guide. Because the rectifier is positioned towards the front connectors, positioning the heat sink for the 3V rectifier required the heat sink to be positioned in the opposite direction.
After some trial measurements, I hung the 3V board inverted from the metal wire bracket. I modified the original 5V heat sink to attach to the 3V rectifier and face rearward. I drilled and tapped 3mm holes so I could properly attach it to the frame. It was a neat fit since the rear of the guide is raised with spacers, and this allowed me to slip the heat sink under the wire guide and direct attach to the frame.
Replaced speaker, added new charge port and mounted new battery with double sided tape and tie wrap for extra security. Rerouted wires as originally placed. G