Brother International DB2-B791 Service Manual - Page 51

Problem Cause Check Solution Page Thread breaks frays Burr in thread path --I Blunt needle tip Remove with sandpaper. Replace needle. 4 Improper needle Needle facing, installation - height Wrong needle for application Needle size, length Bent needle , blunt - Needle tip Blunt rotary hook point Rotary hook point Reinstall needle. 4 Replace needle with larger count needle. Replace needle. 4 Replace rotary zr / hook. Improper threading Threading Rethread. 4 Poor presser foot contact Presser bar pressure Presser bar height Skipped stitches --I Needle bar rise dImproper needle to rotary hook timing _1Needle thread remainder too short; does not remain in material. i Bobbin spins during thread cutting and bobbin thread remainder gets too short; won't rise. Needle bar height Needle to rotary hook timing Bobbin presser spring Tighten presser foot adjustment screw. Adjust presser bar height. Adjust needle to 31 rotary hook timing. Adjust needle to 31 rotary hook timing. Tighten presser foot adjustment screw. 31 Adjust pretension. 5 Replace bobbin presser spring. Thread take-up spring tension too weak, won't raise bobbin thread. Thread take-u spring tension Adjust take-u 5 spring tension. - 54 -