I finally had some time to get back to work on my gang car. I unwound the top coil wire (#1) and found that there were 4 spots on the wire where the insulation had worn off, exposing the bare wire. So I used a small shrink tube on each spot to re-insulate the wire. Then I unwound the bottom coil wire (#2) and found that the insulation on this wire was in good condition.
I re-wound the bottom coil wire (#2) on the Field Assembly and then re-wound the top coil wire (#1) in the opposite direction. I soldered one end of the bottom coil wire (#2) to a terminal on the Contact Plate Assembly (50-38). Then soldered one end of the top coil wire (#1) to the other terminal on the Contact Plate Assembly. The remaining ends of the bottom coil wire (#2) and the top coil wire (#1) were soldered to one side of the brush plate (50-59). The other side of the brush plate was still connected to the grounding spring below the Reversing Slide Assembly (50-27).
The Gang Car works great - reversing as it should!
Thanks to everyone for your responses!!!