Bought this nice vintage instrument today. It’s a 1922 Gibson MB-1 mandolin banjo, manufactured in Kalamazoo, Michigan by the then-Gibson Mandolin-Guitar Company. It’s in excellent condition. All of the tuners work and hold tune well. The banjo head is an original calfskin with no tears or other damage other than dirt and wear, with “Joseph Rogers Son PIONEER” stamped on the interior. It’s open back; from the wear around the edges on the back it never had a trapdoor resonator. The brass armrest was in the wrong location so I moved it back to where it should go. It may also be missing a tailpiece cover. It’s missing one bracket hook and hex nut; I ordered replacements today and will restring it (or have it restrung) since I have no idea how old the strings are (certainly not original, though).
Gibson factory order number (FON) is 11628-18, which dates it to 1922 per Joe Spann’s Guide to Gibson 1902-1941.
It sounds nice. I don’t really know how to play it yet, but as I mentioned, I was able to tune it and it seems to be staying in tune pretty well.
Here are a few photos: