This is a rough edit of a broken Shimano 105 STI 5600 left shifter that wasn't shifting that I pulled apart in order to work out how they worked. I will try and add more details as time goes by. It kinda exploded at the end, so I will add more photos if I can work out how to make it organised. Note the broken Pawl shown in one of the last photos, which is a common problem in 5600 shifters I've been told, but resulted in the unusable shifter. At least it entertained me one last time for an afternoon!