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 :- )
Last edited by Mickey2; 07-07-2016 at 02:45 AM.