I just came across the following from Michael Heiser in an attempt to defend Sola Scriptura:
Why Do You Think The New Testament Needs To Be FIXED?
One of the questions asked is "Where is the New Testament insufficient?" but (1) where does the New Testament say it is sufficient? (2) that public revelation would cease with the death of the last apostle? and (3) doesn't the Protestant doctrine of Sola Scriptura teaches that the Bible as a whole (i.e. all 66 books ["tota scriptura"]) is formally sufficient, not the New Testament merely?
Anyway, for those who want a good refutation of Sola Scriptura, see:
Not By Scripture Alone: A Latter-day Saint Refutation of Sola Scriptura