Malcom,
If, as you mention, that the insulation on the wire is cracked and or has come off, then send it out for repair!!!!
You will see a lever protruding from the top of the locomotive:
This, Locomotive #2018, a 2-6-4 wheel arrangement, has a THREE position E-Unit and is probably in the Neutral/Stop position, causing the locomotive to buzz/hum, but not move.
1-Move the lever;
2-Lay the locomotive on its side;
3-From a D.C. transformer just use about 3 volts and carefully touch the positive wire to the metal contact roller, which is between the wheels;
4-Touch the negative wire to a section of the locomotive body, for ground.
The wheels should spin, but if it still buzzes, or hums, but not move, then it is defective!!!!
The 3-Rail system has the two outer rails as ground/neutral and the center rail is the power bus rail.
http://www.tandem-associates.c...trains_2018_loco.htm
Ralph