The hum is most likely the E-Unit, most of them do have a buzz when they're active. The reason you don't hear the hum with the lever set to forward is the E-Unit coil is not energized in that setting.
Sorry to say, normal operation. Although the E-Unit will consume some power, I suspect the difference in operation is primarily attributed to resistance between the transformer and the locomotive, that would be the power wiring and the track joint resistance.
Sorry to say, normal operation. Although the E-Unit will consume some power, I suspect the difference in operation is primarily attributed to resistance between the transformer and the locomotive, that would be the power wiring and the track joint resistance.
