This animation shows one of the cases that can lead to skipped stitches in a chainstitch seam.
A chain stitch is formed by a needle thread and a looper thread. During the upward movement of the needle, the so-called needle rise, a thread loop is formed on the scarf side of the needle. This loop is picked up by the looper. However, if the needle thread does not form a loop or forms an insufficient loop, the looper cannot pick up the needle thread. The result is a so-called skipped stitch.
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