Can Originalism Be Indeterminate?

Here is one way to think about the discussion of history and tradition in Rahimi: If we cannot determine what the relevant original public meaning is, then we should rely on post-ratification history and practice. 

One problem with the proposition as stated, though, is that I'm not sure whether originalist judges would concede that sometimes the relevant original public meaning is unknown or inconclusive. It seems to me that originalists always think that there is an answer under that method. Reasonable people may disagree on what that answer is. Or the answer may conflict with subsequent judicial precedent. But I can't recall an opinion in recent times that says something like: "Unfortunately, the original materials are obscure or not helpful, so we need to turn to something else for guidance."