John C.,
Were you able to get the sound working again? It has been four days since your last post. I hope you were able to restore the sound. I purchased the Lionel 1931250 Greyhound Challenger #3977. If the sound cuts off on my Atlas O #5 switches, I plan to add the YLB (Your Last Battery) that Gunrunner John sells. When the engine arrives, I will check the tender for a battery clip. Lionel did not include them in recent engines.
Sincerely, John Rowlen