1. Edit to Tape window / Video Tab / lower right corner (Audio Output settings) / click & select "All On"
2. If that don't work, restart FCP & do the above again
3. If that don't work, restart machine & do the above again
3. If that don't work, check your cables / swap out for new ones (I had a bad cable a few weeks ago...went through EVERY troubleshooting trick in the book - couldn't get machine control of my DigiBeta deck through my Kona card. Went over to the router while looking at my monitor and wiggled the cable = VTR OK! Stupid cables.).
When life gives you dilemmas...make dilemmanade.