In 1934, Vibroplex began advertising the “Martin Junior,” which was an Original on a 3” base instead of the standard 3.5” base. Except for the base width, everything else was the same as on the Original. However, Vibroplex had apparently been making the same bug on special order since about 1920. Maybe the early ones should be called the “small-base Original” but to almost everybody they’re a Junior.
Later on, the model was called the “junior-model Vibroplex,” and it was discontinued about 1939, when the Zephyr, Champion and Deluxe Vibroplexes were introduced. Late Juniors have a black crackle base, some with pinstriping, and it’s possible that nickel-base Juniors exist, although none are known to collectors. Colored-base Juniors were never advertised. One green-base Junior was found, but the color was sandblasted off because the owner thought it wasn’t original.