MS de Vries Lentsch, 14,85 m, stern tube sealing

I wonder if there is anyone who has an experience/advice regarding refurbishing of the aft seal of stern tube. The technical drawing is attached and the seal marked. Thank you in advance, Pit

thank you, exactly as you said, after 40 years in service, disassembly was not easy. The seal itself is fixed within plastic tube and secured by another plastic ring. Up to now I was not able to find any similar so I assume it will end up with some modification to accomodate a contemporary seal.