Soldering rail joints or even jumpers may get the job done, but I don't think it is the best practice. I almost never solder anything to do with track. I say almost, because there have been cases where I did solder feeders to some switches, because my regular method wasn't as secure as I liked.
What is my regular method of adding feeders? I use crimp on 1/4" tab connectors. The way they work is, you just shove them into the bottom of the GarGraves rail. This trick, as best as I can tell, goes back to the old Marx lock on.
Carl is correct, while you may have gotten around the original problem, by swapping out that section, you never discovered the root cause. There's really nothing that can go wrong with the track itself, therefor it must be a function of the pins, and poor contact.
