In the stuff I helped sort out for a fellow on Monday, there was a really nice T magneto horn with a brass bell. I don't know if it works, but it is in good shape. The bell is dent free and shows where the black paint has been partially stripped.
I had one on my 1915 tourer, but have only ever seen one other. He is unsure about an ebay listing to sell it.
Looking for help.
Allan from down under.
I had one on my early in the year 16. They are pretty scarce. If it were mine in the condition you indicate, I would ask $300 - $350 and see where it goes.