I don't ever remember there being a ferrule there but it looks like it could do with one, or use a more rigid section of outer. BITD we used very tightly coiled SS with a ferrule built in (stupidly expensive nowadays for the original) or try a more modern outer?
SS means stainless steel, a quick Google will alert you to the purveyors of campag rear mech outers for a lot of money!!
As mentioned, from memory we never used ferrules there but the same memory recalls the outer fitting tight in the first outer ring of the mech. I wonder if someone else has a better memory than me