The 404 is the little brother in the 400 series. The 401 is a zig-zag machine with both built-in stitches and accepts additionals cams, and the 403 is a zig-zag machine that needs the cams to produce the zig-zag and decorative stitches. The 404 is a straight stitch only machine. Some people claim that without the extra mechanics within the machine, the 404 is quieter and smoother running than it's bigger brothers.
My 404 does not have the 'A" suffex. This means the machine was not made in the Anderson, South Carolina factory.
It does have the "flip-up" bobbin winder typical of the US made machines.
And, like all the US made machines, it has a single thread take-up lever.
See? Made it the U.S.A.
Some sewing machines have the capability to drop the feed-dogs. The 400 series lifts the throat plate, instead.
Please forgive the poor picture. Singer had several ways that they wired up the power and foot pedal. Sometimes, they used a single 3-conductor plug. This was common on 'portable' machines in a carrying case. Other times, they used 2 separate plugs: one for power, and another for the foot pedal. This was more common on machines installed in cabinets. This machine has that 2 plug configuration.