Repairing TNA Trains

Something doesn't look quite right, the red wire seams to have been replaced at some point as usually you tend to get a more semitransparent insulation on the wires and this one is very opaque, however I'm not sure if this is true on non Japanese locos. I think replacing it would be a good idea, how ever before that you could use a piece of wire to join the two sides as a test to see if that's the problem