looking at my old sewing book...If any of these look like it
might be "it" then I'll go to the page needed and send it to you
Needle backwards
Tension upper too tight
Debris in tensions
Incorrect needle
Lint pack in lower race
Thread too thick
Needle too thin
Poor thread or old
Burs on thread handling mechanism
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This book is from 1979, but here's what it says about needles
Size 11/75 =use for Batiste, Taffeta, Chiffon, Find Silk, Cottons, etc.
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Size 14/90 =use for Cotton, Flannel, Medium weight fabrics
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Size 16/100=use for Denim, Gaberdine, Drapes, Heavyweight materials
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Size 118/110=use for Canvas, Upholstery, Heavy material or top stitching
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this also has a list for leathers, Size 11/75= 14/90=16/110
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Size 9/65=use for Delicate and Sheer Fabrics, Find Lace
Size 11/75=use for Lightweight fabrics, Single, Double knit, Tricot Jersey
Size 14/90=Medium weight knits
Size 16/110=Heavyweight knits, Heavy elastics, Bonded Knits
==================================
Size 11/75=Lightweight knit with stretch, Jersey, Tricot, Qiana
Size 16/160 Heavyweight Stretch Fabrics, Some Suede
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ANY SIZE..if it is puckering, jamming or breaking, it's no good.
Size
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I never knew most of these sizes, or else didn't bother about being so careful to match the needle to the fabric. In fact, most of the time==I'll admit this==most of the time I don't bother to even change the needle till I start having some trouble with it.