The most common cause of a sewing machine skipping stitches is a problem with the sewing machine needle. The needle may be slightly bent, even if you can not see the bend. It may have developed a dull point from use, or it may have a nick in it.
How will you regulate the length of the stitches if you notice?
Answer: The length of a stitch is regulated by the thumbscrew in the slot on the front of the uprise of the machine. To LENGTHEN the stitch, loosen the thumbscrew and move the lever DOWN. To SHORTEN the stitch, loosen the thumbscrew and move the lever UP.
Why do my stitches look bad?
Needles come in different sizes for a reason. While your small needle is great for sewing together thin cotton, once you start working with thicker materials or lots of layers, you need to get out a larger needle. Mis-threading the machine is also a problem that causes ugly stitches but is a simple fix.
Why are my stitches not straight?
If your thread is pulled tight on the underside and not forming an even stitch then (counter-intuitively) it’s usually the top thread tension that’s wrong. Sometimes very lightweight fabrics such as sheers can get dragged down into the machine so it’s a good idea to use a straight stitch plate.