I've found the bracket that holds the cable to the engine case is bent wrong from the factory. Causing the cable to rub the metal sheath, the friction wears and abrades the cable causing it to break. You can remove this bracket and bend it in a vice solving the problem.
See: http://www.rickramsey.net/TE610mods.htm#clutchcable Mine was rubbing too. I just gave it a little tweak in a vice as well.