This series of machine are kind of oddballs in the Singer lineup. Highly regarded by some, snubbed by others... snubbed mostly because they take an odd sized needle, a 206x13. They are readily available, but not in the extensive range of sizes and point/eye types as the more common 130/705.
The 206 was the very first zigzag machine Singer ever made, and for that reason alone it's a prize. But it's also a really, really nice stitcher.
That knob on the front allows for left-center-right needle position, and also for width of the zigzag stitch. It's actually a really easy-to-use mechanism; a "checkerboard" stitch can be made simply by turning the lever back and forth while stitching:
The back is kind of cool, with a rod across it:
This machine has a cleated timing belt, and a front-loading rotary hook:
This model 206 machine is sold.
Other machines in this series (306, 319) will be added later....