Brother International LK3-B438E MKII Instruction Manual - English - Page 59

16. TROUBLESHOOTING Problem Cause Check Remedy Page Upper thread breaks. Upper thread tension is too strong. Upper thread tension Needle is installed incorrectly. Needle direction Thread is too thick for the needle. Thread take-up spring tension and height are incorrect. Damaged or burred rotary hook, needle hole plate or needle. Thread melting (synthetic thread) Thread and needle Thread take-up spring tension and height Damage or burring Thread edge Adjust the upper thread tension. 23 Install the needle so that the groove is 21 facing forward. Use the correct thread for the needle. 21 Adjust the tension and height of the 24 thread take-up spring. File smooth or replace the afffected part. Use a thread cooling device (optional). 55 Lower thread breaks. Skipped stitches occur. Lower thread tension is too strong. Corners of needle hole plate or bobbin care are damaged. Clearance between needle and rotary hook tip is too great. Incorrect needle and rotary hook timing. Driver is contacting needle more than is necessary. Lower thread tension Damage Needle clearance Needle bar lift amount Clearance between driver and needle Adjust the lower thread tension. 23 File smooth or replace the affected part. Adjust the needle clearance. 31 Adjust the needle bar lift amount. 30 Adjust the driver needle guard. 31 Needle is bent. Bent needle Replace the needle. Needle breaks. Needle is installed incorrectly. Needle direction Needle is striking the button. Needle down setting Needle is touching the rotary hook. Needle clearance Needle bar lift amount. Install the needle so that the groove is 21 facing forward. Refer to "6 CHECKING THE 20 SEWING PATTERN". Adjust the needle clearance. 31 Adjust the needle bar lift amount. 30 Needle is bent. Bent needle Replace the needle. Needle is too thin. Needle and thread Use the correct needle for the material. 53 LK3-B438E Mark II