flashygreg
Hello & Welcome to the Forum!

I'm a tubular track person, but....
If you have a multimeter, you can check each piece of new track for continuity.
Take your terminal section, attached to your transformer, and add the new track to it, one piece at a time checking each piece for continuity. If the track is bad, the lack of continuity will identify the bad piece(s).
If you have a section that show a lack, clean/polish the pin's & female end 's(hole's on other end of the rail) with emery cloth then check it again.
If the track has good continuity, but the loco still stops, you can try adding a feeder line from your transformer to the dead spot.
Hopefully Trainlarry will have an answer, if my suggestion doesn't work for you.

Happy Rails!
Dave