Kenmore Sewing Machine Stitch Length linkage movement

 Sewing machines often freeze up, as they age, if they aren't kept oiled, and used, because the old oil dries up, gluing moving parts together, so they can't move, sometimes, they move a little, other times, not at all.

The cure, is to clean out the old sticky oil, usually with qtips, or a skinny paintbrush, dipped in  rubbing alcohol, or unscented kerosene, between the parts that should move, and the parts they should move against. It takes several cleanings, then oiling with sewing machine oil, or TriFlow oil, to free most of these, and in the extreme cases, a solvent, like WD40, may be necessary, but due to WD40's tendency to draw dust, which draws moisture, and the tendency to dry to a waxy substance, WD40 must be removed completely, and replaced with sewing machine oil, after you free up the stuck parts.

Video shows how most vintage 148.xxx and 158.xxxx Kenmore sewing machine models inner parts should move, when you turn the stitch length dial.