The DBX1 needles work in my Jones Vibra handcrank machine, which is a vibrating shuttle. I recall trying one in a transverse shuttle machine, without any luck, but can't remember which machine I tried it with. It is shorter and thicker than the 12x1. Another needle sometimes recommended as suitable for ts machines is MY 1014B (also known as Canu: 34:22:1 and SMx1014B). It is also thicker than the 12x1, but a bit longer.
These alternates are worth trying, and might work in your machine, but I have several transverse machines, most of which use the 12x1. Two exceptions are the Jones Hand and Singer 48K. The 12X1 needles can be found, with patience and luck. They are also known as System 339, and Boye 23.
Have fun with your machine -- and at the Seattle TOGA! I'm sure you can get assistance there with threading the shuttle and fitting the needle.
Dianne in Colorado