Cable bolt's good. (The slack is between the plastic thing under the bottom bracket that holds the cables and the shift lever, somewhere. I imagine a stripped cable anchor bolt would result in slack all the way through. Am I correct?) Cable seems to be running under the bottom bracket correctly. (I even cleaned out a bunch of gunk in that area.)
At risk of sounding thick, how exactly would I go about looking for a frayed cable, and where, within all the stuff up there? (My shift levers have that freaking thumb trigger, being Sora, so that may impact where I have to look. The book is not helping here.)