I would suspect only real fix would be to remove dam and start over. Any other suggestions?
That's right. I would drain it by cutting the dam in the late spring, then rebuild in late summer after it dries up. Remove all trees, roots, and stumps, cut a new core.
In the long run, it might even be cheaper to fill this one in and build a new pond below it, considering all the sludge that will be in the existing one. That's what I SHOULD have done with my renovation, just pushed all the brush in, and the old dam on top of it.
