To eliminate this problem, measure the gap with a feeler gauge, and insert a brass or hardwood shim of the proper thickness between the heelpiece and the rim. The neck must seat firmly. Once you have found the proper neck angle for your playing, you may wish to have the heelpiece re-cut to change the angle permanently. A small amount of wood is removed from the area around the lag bolt that did not receive a shim . Re-cutting the neck angle is almost invariably a better solution to the proper neck angle than shimming, once the proper neck angle has been determined.
Shims can and do affect the tone of a banjo.
However, if you do not have the proper tools, it is very difficult to recut a heelpiece yourself. Fortunately, for us, Wayne Rogers, the owner of Gold Tone banjos can do this for a reasonable fee. The Gold Tone banjo web page may be found by clicking here. Some people also alter the tone with the coordinator rods. I am wary of this, because if you throw the tone ring out of round, you can keep it from vibrating properly.