Suppose there is an old question on mathOverflow, asked by someone else, which has been voted up a quite decent number of times, and received several answers which have also been voted up, but no complete answer was given (and none was accepted). Suppose I would like very much to know the answer to that question, and that I think there should be specialists out there who know that answer, but don't see the question as it is drown deep in the archives.
What would be the ethical way to bump up this question and make up visible to all, in the hope that it finally receives a complete answer?
I can think of several ways in doing so, none of them completely satisfying: (a) make a trivial edit to the question the make it bump up. (b) make an edit to the question explaining why it has not been answered completely. (c) re-ask the part of the question that has not been answered as my own question.
What do you suggest?