Brother International HE-800A Instruction Manual - English - Page 100

16. TROUBLESHOOTING １６. TROUBLESHOOTING CAUTION Turn off the power switch and disconnect the power cord before carrying out troubleshooting, otherwise the machine may operate if the treadle is depressed by mistake, which could result in injury. １６-１. Upper thread breakage Cause Needle Threading Thread path Check Needle facing Needle installation height Bent needle Blunt needle tip or burr Needle and thread Upper thread threading Lower thread threading Flaw or abrasion on the thread path Remedy As viewed from the direction of the face plate, attach needle so that the notched part of needle faces frontward. Insert the end of the needle shank so that it touches the top edge of the needle hole of the needle bar. Replace needle Replace needle Replace needle that fits the thread Thread the upper thread correctly. Thread the lower thread correctly. Polish with buff or replace the part. Especially, pay attention to finishing around needle plate hole. Page 57 58 60 - Needle plate hole Flaw on the rotary hook point and rotary hook edge Flaw on the rotary hook holder Polish with buff or replace the part. Polish with buff or replace the part. Check flaw here 3996Q - Adjust the rotary hook - overlap amount. 3997Q Thread tension Zigzag thread upper Adjust the upper thread tension appropriately. thread tension 62 Bar tack thread upper Adjust the upper thread tension while checking thread tension stitches. (The stitches on top are the upper thread 62 and the stitches underneath are the bobbin thread.) Thread spring take-up Thread take-up spring Loosen the thread take-up spring tension or shorten tension and stroke the stroke to such a degree that does not cause double hooking. Adjust it while checking bar tacking 63 stitches. HE-800A 92