This direct command may be useful for diagnosing the issue with the sound loop: no sound, or corrupted sound.
If you don't already know how to send a direct command, check this link below:
Steps
1. Depending on the time of the day in the unit, send the following direct command where NN is a track number. It may take up to 10 seconds for the sound to change, so, give it at least 10 seconds before each try:
Daytime Soundloop
m02NN
Example:
m0201
Nighttime Soundloop
n02NN
Example:
m0217
Track Ranges
01 to 17
Note: The change is not permanent and will get reset back to the original when the day/night cycle changes.