Regarding the earlier reply from Don M. Whether I intend to sing or not, I find that having the words of a song in front of me, especially a song that has not been played for a while, absolutely essential for recalling a half forgotten tune. Simply by seeing the words of a song that I used to know well, I find that I can recall the tune much more easily. In some cases, I simply cannot instantly recall old or obscure songs in their entirety (or at all) without seeing the words.