This is a Kenmore model 158.1430. The model number is irrelevant to this post because I have found that in general, the vintage Kenmore 158 series is a very high quality sewing machine. They feature powerful motors, good stitch selections, and probably the best button hole system on any machine of its vintage. In all regards, they are very capable, reliable, and consistent sewing machines. They are a very good value for anyone interested in a vintage sewing machine.
But… one comment I have heard fairly frequently is that there is a noticeable “knocking” noise when the machine is sewing. There is nothing wrong inside of the machine and I have found this to be consistent with most of the Kenmore 158 series. It is less noticeable in some machines than others, but it is still noticeable.
The cause of the noise is the thread spool moving up and down on the spool pin when the machine is sewing. The movement isn’t very noticeable, but if you watch closely, you will see it. Every time the thread spool drops back down, it will hit the top cover. Because the top cover is metal it causes a “knocking” sound, even if you are using a spool pin felt.
Looking at the underside of the top cover, you can imagine how this happens… the top transmits the sound like the head of a drum. To fix this, all that is required is something to insulate and dampen the sound. I have found that a small layer of packing foam (like the stuff used to pack china) is perfect… it is thin, it is soft, it does not degrade or shed fibers, and it is very easy to cut.
Place the top cover over the foam sheet, trace the outline, cut inside of the line so it fits inside the cover, and just lay it in place. If it is cut a little oversize, it will stay in place. No gluing is necessary.
If you look at the cam mechanism in the machine, you will see that there are no moving parts that will hit the foam, and the foam will lay safely on top of the mechanism without jamming any mechanism inside the machine.
The difference in the sound is noticeable. The knocking noise is eliminated, and the overall sewing experience is improved.
Easy fix… try this on your Kenmore