Sounds very similar to the problems I've been having. Everyone told me to go with lighter discs, and I finally got advice that helped -- to go with heavier discs. I'm now throwing around 170g discs, rather than the 150s everyone was suggesting. I think the Buzz you suggested was a good start. With the wobble he's having, the lighter discs just make it worse.
As far as spin, I found my problem with spin was related to timing. I talked to people on the forum, and they helped me realize that my timing was off, and I was pulling too early. I've been working on changing my timing out in the field, and it's helped considerably. I'm not getting significant distance improvement, but the disc is going straight, and it's spinning! This may or may not be your father's problem, but I even had lessons from several pros, and they didn't pick up on it. I don't think it's obvious unless you specifically look for it. It wouldn't hurt to watch to see if that might be the problem.