First take off the resonator and check the co-ordinator rods to see if all the nuts are tight enough. All of our banjos are now built with a two way adjustable truss rod. Next check the fingerboard. It should bow a little to prevent the strings from buzzin.
The easiest way to check is to site down from the nut to the banjo rim along the fingerboard edge. You can compare the binding to the straight D string. If you will push down the 3rd string on the 1st and 22nd fret together then there should be a distance of 0.5-0.7mm (5/256 – 7/256“) between the 7th fret and the string. If the distance is greater there can be trouble with the intonation all along the fingerboard. If it is lower than .5mm, you might hear buzzing.
When everything fits correctly then there will be a 11/64 to 12/64“ space from the open 3rd string to the 19th fret on the fingerboard.
When the action is too low,lose the nut out of the rim and tight the nut inside the rim. Strings will go up to the fingerboard.