Good grief, ifn ya need some material for a tip, I think I know where there is a box of them.... My shop..... The way it sounds, I think it is screaming for an applied tip put on it, if ya need help, there is always my shop if ya feel like a road trip.
I just bought a nice horn from Roland that sounds just like the one you are describing and he did no engraving, just a screw tip and it really turned out nice, that's why I bought it:)