1. When selecting, check whether the machine head is bright, whether there is paint peeling and bumping, whether the electroplating layer of the needle plate, push plate, panel, upper wheel, etc. is in good condition; whether the platen is straight, and whether the paint has cracks or local discoloration; Whether the frame is broken, peeled off, or twisted; whether the gap between the upper and lower shafts and the needle bar meets the standard requirements.
2. Remove the belt, lift the presser foot, turn the upper wheel gently, check whether it runs freely, and whether the needle rises and falls in the middle of the needle plate hole.
3. Whether the sound of the machine is soft when rotating.
4. When trying to step on and sew, first use two layers of thin cloth to try sewing to check whether the stitches are flat and even. Then try sewing with the original fabric to see if the stitch length can reach 3.6mm, and there are phenomena such as the seamless material does not go away or the sound is abnormal.
5. For more specific inspections, there should be a sewing machine maintenance and security worker present.
