This sequence of photos show an example of a rib having been damaged along the top from repeated removal of the front over the years and needing to be built up in height.
The second photo shows the damage along the top of the rib.
In this case I removed the original lining first. I struggled to find a quarter sawn piece of rib to match the fine medullary rays of the original rib, so decided to use a piece of slab cut maple instead. It was bent with a bending iron and chalk fitted to the original rib.
After carving it back and replacing the lining, I stained it, applied filler varnish, scraped it and finally retouched it to match in with the original.