Change overlock needles
Many overlockers have several positions where the needles can be used to achieve different stitches. The changing of the needles is demonstrated at the time of purchase and can be read in the manual. Often, however, the reference to the following is missing: It may be that you want to replace the needles in the middle of a project with a pre-set seam.
Here's the tip: Never remove all needles from their holder at the same time. So it can happen that for the following stitch to be sewn and already selected, the distance of the needles is not correct, the machine is blocked, a needle pushes open and breaks and / or fabric or seam allowance is already cut off. :-(