I'm sorry to hear that he became blocked again. Maybe he keeps getting a mucous plug I think that's what it's called. Some cats get this and it'll also cause them to become blocked. Why did your vet say that he wasn't a good candidate for PU surgery? If he has a narrow urethra then it doesn't take much for him to become blocked. This is what my Storm had too. Lots more prayers and positive thoughts are being sent his way. Please take care. (((HUGS)))