I'm sorry your husband is having so much trouble with his wrap. As Bill said, tighter is not better. That's the challenge for a surgeon, and why it's so important to have the surgery done by someone who had done many, many Nissen procedures. It needs to be tight enough to hold the acid in, while allowing food to pass easily. It's an art form, and it takes lots of practice.
I would suspect that they will want to do a dilatation to stretch it and try to make it looser. The wrap is swollen in the early stages of healing, and could be swollen even now, but liquids should be able to go in fairly easily.
Try not to jump to conclusions. You may be able to get things straightened around without a redo surgery. If things don't get better for him, it would probably good to get a second opinion.
When you try to locate a surgeon to give the second opinion, try to do careful research. Make calls to find out who local GI docs recommend. Check the hospitals, ask friends in the medical field...you'll want to find the best person in the area. Also, there is always the option of going to a center where they are used to dealing with difficult cases.
Take it one step at a time, though. See what they can do for him.
Good luck! Hope things get better quickly.
PS--those are the pre-op tests that are typically done.