Many of them were based on a Singer class 15 machine, and are commonly known as "Singer Clones" - read a bit more about them here. If your sewing machine looks a lot like these machines but has an off brand name, chances are you have a generic or clone machine.
The overall condition of your machine is one of the biggest factors in estimating a value.
For the first time the most complete story of a forgotten giant is brought to you by Alex Askaroff. The castings were marked with the serial number right in the earliest stage of manufacture.
The machines were miles from completion, packing and delivery. They all effect the purchase/receipt date All Singers up until 1900 have no letter prefix and came from several factories around the world.
Here's an article listing the Top 5 Best Vintage Singer Models, and many people who collect and sew with vintage Singer machines do love and seek out these particular models.
There were a small handful of manufacturers who made "generic" machines in the mid 20th Century (like the Morse pictured above).
Or you can look at this brief history of BERNINA sewing machines at to see if you can find a similar model to yours.Actually, there are lots of variables to estimating the worth of an old sewing machine, so let's look at the most important; the make/model and date, the condition, and any extras that may be included with the machine.There aren't any comprehensive lists for identifying models or manufacture dates for old BERNINA machines available online.There is a lot of controversy over why there were two lots of numbers.The most likely answer is that the larger number was the total number of machines produced by Singers when they only had a few factories and could keep up with and control the production output from Britain and America.