See this post is a bit dated so he probably got er fixed, but for future reference, I wouldn’t even try to repair it in that location. Find both ends and use the old wire to pull new wire through. Use something more durable or protect it/fix the sharp edge ( if you can get in there). If nothing else, pull new wire mark location where it’s rubbed before, pull it back enough to access that part of the wire. Zip tie a piece of split hose or wire loom over it and then pull it back into location.
Maybe consider insulating or protecting the rest of them too if they move with the slide.
Depends, does the wire move with the slide or was it just stripped bare when it was pulled through during assembly?
