While my go to machine is a 403 with all kinds of attachments, I'd say you can't go wrong with that era Kenmore. I have had a couple I got rid of and regretted. The Singer is worth a bit more money. Either one should clean up nice. Either one should handle most fabrics. Parts might be more readily available for the Singer. New wiring can be found for either machine.

You know, I'm thinking maybe my hairdresser should go on Kijiji and find her own machine! Now that I started comparing both, I don't want to part with either! I do, however, thinking the Singer has a more stylish look to it. I only bought the Kenmore to do zigzag sewing, but now I realize I got a much better machine than I'd realized.

i'd keep the kenmore.

I have a Singer 403A, and I've used it to assemble a lot of quilt blocks. Piecing the blocks, I used my FW, but the blocks were 14.75 inches square, so it got to be pretty heavy for the FW. Nothing wrong with the machine, but the 403-A handled it much better. You may be better off keeping both machines, but if I had to make a choice, I'd keep the Singer!
Jeanette

Yes definitely this!

For a Kenmore it's hard to to compete with a Singer. If it's well built it should be given a fair chance, which means cleaning, lubrication and actually using it for a while. If the grease looks old it should be replaced anyway, and from what I have observed most of grease is just squeezed out to the sides on the first turns after application, and never reaches the gear again; so I think a little smear more frequent will work better. This might depend on gear setup and grease though.

I searched up a picture of the Kenmore model, and it looks like some of the cams for it are double layered. It means back stitching and stretchy stitches. The cam function is probably of a fancier build than on the Singer 403 :- )

I'd keep the Singer-because that is precisely what I did. I have a 401 in a desk cabinet that I bought in 1959. I could not part with it. And, I still sew with it from time to time.