1. Select to see whether the head is bright, whether there is paint stripping and bruising phenomenon, needle plate, push plate, panel, upper wheel and other electroplating is intact; whether the table plate is straight, paint but whether there are cracks or local discoloration; whether the frame is broken, paint off, twisted; whether the upper shaft and lower shaft, needle rod gap meets the standard requirements.
2. Remove the belt, press the foot, gently rotate the upper wheel, whether the machine needle is running freely, whether the needle is lifting in the middle of the pin hole.
Three, whether the machine is soft when rotating.
Four, try to step and sew, first use two layers of cloth to test the seam, check whether the stitch is smooth and even. Then try to sew with the original cloth, to see if the needle foot length can reach 3.6 mm, seamless material does not walk or sound abnormal phenomena.
Five, more specific testing should be performed by the sewing machine maintenance worker.