Pfaff dorina 75 Owner's Manual - Page 49

Faults and how to remedy them Thread forms loops Cause: Thread tension not properly regulated Needle thread not properly threaded and/or bobbin thread not properly wound Thread size not suited to fabric Thread check spring not working properly Remedy: Read instructions for regulating needle- and bobbin thread tension Thread machine properly and/or wind bobbin thread correctly See "Fabrics, threads, thread sizes and needles Have spring replaced Shrinking or puckering of the seam Tension too tight Sewing foot pressure too strong Read instructions for regulating needle- and bobbin thread tensions Read instructions for regulating sewing foot pressure Irregular stitches Needle- and bobbin thread of poor quality Bobbin thread unevenly wound Machine needs oiling Dust and thread in shuttle Wrong oil used, has now clogged machine Drive belt tension too tight Use top quahty threads Re-wind bobbin Machine does not run freely and makes a noise Read instructions on how to oil Read instructions on how to clean shuttle race Clean machine carefully and re-oil with top quality oil Loosen tension of drive belt 48