Initially I had a bad wire AND a bad connector. Opposite sides of course! As I diagnosed,I thought it was crazy that the center turn light was used for only that. No reason since the bulb is dual filament and the socket "could be".
So I took the bad one apart and it was the flat wired printed circuit style. I figured out what needed to be done inside to make the center bulb serve as a tail light and off to the parts store I went. When I took the new housing apart I found it was discreet wires not a printed circuit! I crushed the old dual filament sockets (carefully) to get the correct tabs out. The ones that were missing and needed to do the mod. Popped them in the new sockets and did the jumpers as shown in the thread. All the jumpers were done INSIDE the housing and there is no need to use a diode if wired properly. I did have to carefully grind the housing to allow room for the wires. The housings were super glued back together and then I used aquarium sealant to be thorough. I love the results and do not understand why they did not come this way from the factory.