based on my experience, broken clutch cable mostly occurred at the end section (at stopper-button) attaching to the lever itself, this occurrence usually happened when changing to aftermarket clutch lever and stiffer clutch springs, i noticed that when i pulled the lever, the sharp edge at its inner portion where the button resides slowly eats the stranded cable causing ordinary wear and tear, so i slowly grind the sharp edge to the point it cant harm the cable... now my aftermarket clutch cable is 3 years old already although it has a smaller size compared to the OEM size. beware also of hollow stopper bolt with coin-like knot (commonly called adjuster if am right), its edge can also cause misfortune of the cable when improper installed,