The 8 pin chip to the right of the preset looks backwards.
Pin 12 is the drive to the output fet, without this you wont get the ac on the test terminals, a scope would show you a square wave most likely, a meter would show you the average dc level, and a logic probe would show a pulse.
If theres no ac on pin 12 then it might be something as simple as the device is not in test mode or something, maybe you need to initiate a test by pressing a button or something.