"It's got six tuners but only five strings, so maybe it was a convert? (New nut, bridge, maybe tailpiece?)"

Nope. That's how they made 'em. They used guitar tuners and left one "open," simply because it was a way to get tuners onto an instrument in a manner their maunfacturing standards could handle. The 'zither' banjo was a kludge of an instrument, and nearly universally poor in sound, playability (someone up-stream here has already commented on the problems of changing the head [vellum]). In general, the six-tuners-for-five-strings approach might have been a reasonable approach, but it was typically married to the small 'zither' head arrangement, and was a failure.

I have seen vintage six- and seven-string "five-stringers," most of which did not use the 'guitar headstock' approach. Some American makers did them, but they never gained much popularity. I suspect the 'how long does it take to tune a banjo?*' aspect of the instrument was made even harder to accomplish with the added string.

Bob Clayton


* 'No one knows!'