Interesting, mine was the volume up - it works some of the time but not always. After taking it apart and cleaning it it has made no difference. The up causes it to click like it does down, so Im assuming that the up clicker on the circuit board is not making a good contact. I didn’t look at how easy it was to remove the sheet containing the click buttons from the board. Maybe next time i take it apart, I’ll look, and have a go at fixing it.

Make sure the antenna cable assembly locates correctly on reassembly. It is important to install this down onto its locating lugs, not pushing from the rear of the machine towards the front. There is a small ‘u’ shaped cutout on bottom of the assembly and a metal tab which must locate into the corresponding ‘u’ shaped lug and slot cut into the metal of the top case. If this is not located correctly there is a good chance that the screen will foul when opening and closing resulting in an audible click as it catches the antenna assembly.