There's several reasons why you might not get any audio from the internal speaker. The speaker or the audio jack to output the audio to an external speaker are common causes.
If you have an external speaker with the correct audio plug, try plugging it into the scanner's audio jack to see whether you can hear audio through the external speaker.
BTW - did you mean a "760xlt" scanner ? I don't see any listing for a 76xlt scanner for Uniden / Bearcat.