Brother International Z-8550A Instruction Manual - English - Page 85

15. TROUBLESHOOTING Problem 9 Lower thread is tangled at the sewing start. Spinning of bobbin during thread trimming Lower thread 0628M 10 Upper and lower threads are breaking. 11 Broken needles 0471M 0469M Possible cause • Is the bobbin spinning direction correct when the lower thread is being pulled? Set the bobbin so that it turns in the opposite direction to the rotary hook. • Is there too much thread wound onto the bobbin? The bobbin winding amount should not be more that 80 %. • Is the anti-spin spring attached? (8560A) Attach the anti-spin spring. • Is the bobbin turning smoothly? If the bobbin is not turning smoothly, replace the bobbin. • Is a bobbin other that the light-alloy bobbins specified by Brother being used? (8560A) Use only bobbins which are specified by Brother. 3557M • Is the needle bent or is the needle tip broken? Replace the needle if it is bent or broken. • Is the needle properly installed? If it is incorrect, install the needle correctly. • Is the machine properly threaded? If it is incorrect, thread the thread correctly. • Is the rotary hook sufficiently lubricated? If the oil gauge is down to the lower reference line in the oil gauge window, add more oil. • Is the upper or lower thread tension too weak or too strong? Adjust the upper thread or lower thread tension. • Is the upper thread may be loose because the thread take-up spring operating range is too small? Adjust the position of the thread take-up spring. • Is the needle and rotary hook timing incorrect? Adjust the height of the needle bar. Adjust the clearance between the needle and the rotary hook. • Is the thread too thick for the needle? Use the correct needle or the correct thread. • Is the rotary hook, bobbin case, thread take-up lever or some other part in the thread path damaged? Repair the damage, or replace the part with a new one. • Is the material being pushed or pulled with excessive force during sewing? • Is the needle properly installed? If it is incorrect, install the needle correctly. • Is the needle bent, is the needle tip broken, or is the needle hole blocked? Replace the needle. • Is the needle and rotary hook timing incorrect? Adjust the height of the needle bar. Adjust the clearance between the needle and the rotary hook. Caution • It is extremely dangerous to leave any pieces of broken needle sticking in the material. If the needle breaks, search for all pieces until the whole of the needle is found again. • Furthermore, we recommend we recommend that through steps be taken to account for such needles to comply with product liability regulations. Page 16 16 15 15 15 17 9 47 61* 64* 64* * 15 64* 64* 77 Z-8550A, 8560A