I made almost zero progress for 90 minutes at least. Discarded letters, an uncertain method of entry, unclued entries and some horribly tough clues for the ring entries means almost zero feedback from the grid. I’m nowhere near finished but dinner called and the rest can wait till tomorrow.
I have got the tune, and that helps with the unclueds, but I share CD’s concern about the music box. Especially as there appear to be five potential notes...