Table 9-1.—Troubleshooting Chart TROUBLE PROBABLE CAUSE REMEDY Needle breakage. Incorrect class and variety needle being Use correct class and variety used. needle. Needle loose in clamp. Tighten needle clamp screw. Needle too small for fabric. Use larger needle. operator pulling on the material. Allow machine to feed material. Needle thread breakage. Thread too heavy for needle. Use larger needle or smaller thread. Right twist thread being used. Use left twist thread. Damp or defective thread being used. Use only dry smooth thread. Machine incorrectly threaded. Check machine for proper threading. Needle incorrectly set. Set needle with long groove to the left. Needle thread tension too tight. Loosen needle thread tension. Thread take-up spring out of adjustment. Adjust thread take-up spring. Burr on bobbin case, Shuttle point or Smooth with emery cloth. tension disks. Thread rubbing against presser foot. Adjust presser foot. Needle has burr on eye or point, blunted Replace needle. or bent. Bobbin thread breakage. Bobbin tension too tight. Adjust bobbin tension. Bobbin incorrectly threaded. Thread bobbin to revolve clock- wise. Bobbin wound too full to revolve freely. Remove some of the bobbin thread. Rounds of bobbin thread lapped over one Insure bobbin thread is straight another. when winding bobbin. Bobbin case is dirty. Clean and lubricate bobbin case. Skipped stitches. Machine out of time. Time needle to shuttle. Thread controller spring out of Adjust thread controller spring. adjustment. Drawing of seam. Needle and bobbin tension too tight. Loosen needle and bobbin ten- sion. stitches piled up. Stitch regulator out of adjustment. Adjust stitch regulator. Pressure on presser foot too tight. Loosen presser foot adjustment screw. Feed dog striking throat plate. Feed dog set too high. Lower feed dog to correct height. 9-7