How can I redraw a line in the diagram

[rich2005]

Another way. I wish I had a shortcut method for you. Because of the image this is very hands-on You will be hard pressed for a quick solution.

In the video: https://youtu.be/vcLgq7cP3K8  3 minutes

1. Duplicate layer
2. Fuzzy select the line, threshold 120 to 130 (add any little bits missing as well)
3. Grow the selection by 1 pixel
4. Colors -> Map -> Color Exchange black to red and up the 3 sliders to maximaum
5. Repair the lettering using the clone tool, alignment = registered and clone from bottomlayer to top.





   

( curses, missed a bit )