Do you have the actual Lionel product number?
Have you tried running the volume control back and forth a few times?
Do you feel comfortable opening up the tender?
This looks to be the 1991 version, it has the old RailSounds 1 board. Checking the connections, seeing if the speaker is bad, etc. is pretty much the first steps.
https://www.lionelsupport.com/...;submitButton=Search