Sometimes the clicking is hard to hear. I have had to put my ear right against some units just to hear it faintly. Also a word of caution: when you open these things, the line filter capacitor remains charged with lethal voltages. You want to carefully (with one hand in your pocket) remove the board and short the two large contacts near the middle of the board with a screwdriver. I have done this often, and sometimes it produces a spark, but that confirms the short was successful. I would touch the leads with a screwdriver a few times to make sure. If you wait half an hour, most of the voltage should have drained and you shouldn't have a problem, but I still short it to be safe.