After further troubleshooting I've found that loosening the screw which is responsible for the clicking effect solved the problem. The touchpad needed more space to move. How this could have happened by itself initially, don't ask, magic! So the solution which worked for me: open up the mac book remove the battery loosen the big screw which is pushing the touchpad against the shell a little bit, so the clicking effect is there fully. Hope this helps someone. You will need a whole bunch of specialized screwdrivers for this. I needed 4 different ones.