Originally Posted by
leonf
Couldn't agree more.
One other thing that I should have added. The 15-91 and the 201 which are the sort of "commercial" grade Singer domestics have internal motors. These are not available new any longer. If one of those motors is worn out, the machine is unusable unless one finds another used motor. And when one is talking about a machine say from the 1950's, a used motor will also date to the 1950's.
Domestic machines with externally mounted motors, such as the one shown by leonf are easily available new. So when one of these motors wears out, at least they're replaceable.
FWIW: my mother did some commercial sewing on a Juki domestic machine from the 1950's. The machine was built like a tank. It didn't take long for her to realize that the machine simply wasn't up to the task and she started sewing on a Singer industrial. After she started using an industrial, she never went back to using a domestic machine for any sewing task.