I would say that the coming of electrification played a big role in rebuild activities. Many of the rebuilds that we see are machines that have been converted from treadle to electric. Singer was on the cutting edge of the design and manufacture of electric-powered sewing machines, but not everyone wanted to or could afford to buy a new machine. But I’d say that the majority of sewing machine owners COULD NOT WAIT!! to get rid of the foot-powered drive and take advantage of the new electrical driven power source. I’d say that once electricity became available to them, they wanted to use it.
Many had probably become very proficient with their old machines, and may have wanted to avoid learning how to use a new machine, but changing how the machine was driven may not have intimidated them as much. I think that some of the paint jobs may have simply been an attempt to pretty the machine up after new shiny parts had been added (motor, disc balance wheel, bobbin winder on the belt guard, etc.) that didn’t match the old finish. There were probably as many old machines rebuilt by owner request as rebuilt to sell to a new owner.
Again, I think it was all about money, or rather the lack of it.
CD in Oklahoma