As a result of a derailment, the double wire from the tender to the locomotive that is the connection for the amplified sound feature pulled itself out of the back of the tiny plug-in jack. I reinserted the wires into the back of the jack and plugged the jack back into the little socket (at the back of the locomotive). No sound. Retried repeatedly, including skinning off the insulation and reinserting the wires repeatedly, but no sound. I'm not an electrician. Are than any suggestions short of purchasing a new locomotive-tender set?