I cannot tell you what you should do. I will tell you what I would do. I would just bite the bullet and start over with good stock. Breeding rabbits just shouldn't be all that difficult.
Just a comment. I have raised livestock for years. I have found that it doesn't matter how much you have paid for an animal, if it cannot do what it is supposed to do it is useless. That said, if I were you I would do two things. One, I would turn that buck upside down and get a good look and...
This advice is worth every penny you are paying for it but if I were you, I would replace all the rabbits and start over. If you can find a successful breeder of New Zealands in your neck of the woods that would be a good place to start. Maybe get two junior bucks, one junior doe, and one bred...