Perseverance works
One thing in your
#10 post on this thread you mention,
And worst of all... pressing the brake lever doesn't pull the cable at all...just causes the cable to jump out of the barrel nut.
Which you suggest 'got fixed' previously when you replaced the cable. I'm guessing the 'barrel nut' is the adjuster on the brake lever. It is possible that having released tension in the cable its nipple has popped out of the retaining hole in the brake lever itself so in effect it is no longer attached. You might remember swearing a bit last time you fitted a new cable as you fiddled about getting the nipple to locate properly.. Just a thought.
As another thought it might be worth buying a new cable and pair of end crimps, the little sleeves that go on the cut end to stop it fraying. Having said as much you do need the right tool to cut and crimp them. With all the adjustment that has gone on your present cable looks to have suffered multiple flattening at the brake fixing point and it is possible that it might give up the ghost and start fraying.
Whilst you are doing the front brakes you may as well have a look at the rear ones as well. Call me a tinkerer. The, not so cunning, plan is that you only need one new cable for the rear brake. You re-use the old rear brake cable on the front brake.... or buy two.
One other concern would be the 'barrel nut adjuster' at the brake. I do not know about the quality of your bike but everything I have seen that is modern, and cheap, comes with resin moulded brake housings and really poor quality adjusters made out of something that might be called metal. The resin thread strips and the metal is truly misshapen and generally horrible. Yours may be better quality but if they are not you may as well just glue them in place and accept you will have no adjustment.
