Somewhere between picking up the gilded grasshopper on the roof and attempting to read the note "food for the grasshopper" the gilded grasshopper has vanished. I'm not sure if I sold or scrapped it. But the quest says to read the note and I don't have it, right now I can not complete this quest.

After picking up the gilded grasshopper from the roof, I went around doing other missions and fixing up settlements, by the time I got around to picking up the quest again, I had no note and no gilded grasshopper from which to retrieve the note, I even went back to the hall on the roof but the gilded grasshopper is not there either. Short of an old save (really old), got any ideas?

The note points you to a grave, containing a unique weapon, and some loot.
That old save may be worth looking at.

It also finishes this quest completely.