Warning: this is a newbie thing. Today I discovered that my everyday banjo that I bought two months ago was strung incorrectly through the calmshell tailpiece. The bottom foot of the tailpiece was touching the head, and that did not look right to me, but I couldn't figure out how to correct that. Well today, my new (to me) Morgan Monroe Cascade arrived, and I noticed that the strings came entirely under that foot of the tailpiece and then came through several openings to get hooked on to the tailpiece. That way, the bottom foot of the tailpiece puts pressure on the strings downward, while staying out of contact with the head. (This is the place the old guys will want to laugh).
So I corrected the path of the strings on my old banjo through the tailpiece, and amazingly it sounds better. The string action is better too.
Don't feel bad. I had the same problem when I put on a clamshell. I orginally had the strings coming through the small holes that are there for ball end strings. Live and learn. Keep on picking. Best wishes,
It doesn't happen just with clamshells. I just picked up an Epiphone that had the strings strung under and up rather than over and down, and it has an open-faced tailpiece. Two other banjos that I've bought and resold were strung in that manner, so I'd say it happens all the time. If the first one I got was strung that way I wouldn't have known it wasn't right. My hunch is that guitarists that take up the banjo go with what is closest to what they're used to when they string the banjo.