Hi Joe,
Good to see you posting again and I hope you are fully recovered after your health problems.
From your description of the 'fault' it sounds to me like the Monitor settings are incorrectly set....
Go to PROGRAM MENUS > SOUND > MONITOR SETTINGS and check that the option is set to 'ON'. If this option is set to 'OFF' then the internal speakers and the Headphone output will be disabled, but the LINE OUTPUTS for connection to an external Amp, will still be active.....