This issue is solved. Airforums was a big help and my RV Service Center contributed as well. There were two main issues…one involving fuses on the TV and the other involving grounding on the tail light canisters. Two fuses on the TV were blown which rendered all testing and trouble shooting erroneous. I was somewhat careless while testing the turn/stop/marker
12V circuits and probably blew those fuses by accidentally touching a wire that was charged with
12V to the camper skin. If you see sparks the next step is to check the fuses on the TV. My RV Service Center discovered the blown fuses. I replaced the fuses and started over being very careful not to short a circuit. I used a
12V tester to check the 7-pin connections on the TV and found the configuration standard. I plugged the 7 wire cord into the TV and I then matched each colored wire on the other end and installed the plug-in. The plug-in end plugs into a Pollak 7-pin outlet mounted on the front of the camper. All of the 12V towing circuits on the camper plug in to the back of this outlet and I matched them with the front of the outlet with the test light. With the fuses on the TV replaced I’m thinking I’m good to go. I started with the right backup light and was completely miffed when I got no light. At this point I decided to go to Harbor Freight and buy a 4-pin turn/stop/market kit with tail lights that attach magnetically. But then the miracle happened. When I originally pulled the canisters I noticed that they were not screwed in. The red and white leads from the bulb fed out the bottom of the fixture and the fixtures were just jammed into the sockets pinching the leads but making the canister tight in the socket. Fortunately none of the leads were shorted. To fix this I drilled a 1/4” hole in the back at the base and routed the leads out the back. This got them out of the way of the bottom of the fixture. I also put a small offset on both sides of the mounting bracket. This raised the socket enough that it didn’t crowd the bulb. Rerouting the wires out the back of the canister made the canister loose and it needed a self tapping screw to secure it in the socket. When the screw began to seat the light came on! That was the ground that was needed. The red and white leads on the bulb fixtures are both positive. The ground is wired inside the fixture. In my case the red lead tied to the marker lights and the white lead tied to the turn/stop wire. On the reverse (backup) light you only use the white lead. Just cap the red lead with a wire nut. When you secure the fixture with a screw that provides the ground. Hope this is helpful.
When I turn the left blinker on the TV the left turn/stop wire blinks. But it only operates one side of the bulb when you hook up the fixture and apply the brakes. I’ve owned quite a number of vintage trailers but I’ve never had this much trouble before. 
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