I have two very different short scale banjos with the same problem - past the fifth fret there is no ring/sustain, just a short harsh grating overtone note. Both have nylgut classic strings. One is a Saga 10P that has a Ren head, moon bridge and a brass tone hoop. The other is a converted Vega - skin head, steel tone ring 1/8" thick, Grover compensated bridge. Not too much luck with varying head tightness. Bridge recommendations vary from ultra light/no ebony tip to extra heavy. Anyone else have this challenge and solved it in reality, not theories? Thanks! Banjered