Issue link: https://docs.hic.us/i/445631
219 Trouble examples and Corrective actions Chapter 9 1 2 3 4 5 6 7 8 9 10 11 QS10 2. Trouble examples and Corrective actions 2-1. Thread breakage is highly visible. If the followings seem to cause the trouble, please ask the distributor for information. (a) The gap between rotary hook and rotary hook support is narrow. Timing between needle and rotary hook is too early or too late. Scratch, abrasion of rotary hook. (b) The gap between needle and hook point is not suitable. Bad adjustment of lower dead point and/or upper dead point of needle bar. (c) A play of rotary hook shaft is big in back and forth direction. There is a play on the fringe of the frame. (d) Rotation of the main shaft is not smooth. Abrasion/breakage of neighboring parts of take-up lever drive and/or needle bar drive. (e) A play of needle bar case (in right and left direction) is big. Cause Troubleshooting Bad thread tension Adjust tension. Upper thread 120 to 140 g, Under thread 20 to 30 g Quality of thread is bad. Poor thread flow Use good quality thread. Spray silicone. Direction of needle is bad or needle bents. Adjust to face to the front or to the right a bit. Replace. Applique glue is stuck on needle. Remove adhered glue. Contamination, run-out of oil of rotary hook Clean and lubricate the machine. There are many fine stitches of 0.5 mm or less in design data. Remove fine stitch(es). The fabric is lifted too much against the needle plate. The fabric touches the needle plate too much. Stretch the fabric again so that it touches needle plate lightly. Run-out of oil of needle bar Lubricate. There is a scratch on the thread course. Grind it with sandpaper etc. Replace. Bad height of presser foot Perform adjustment so that height fits to fabric/ material.