SINGER W1977 - Manual (Page 55)

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7. TROUBLE CHART
Section
7
PROBLEM PROBABLE CAUSE CORRECTION
Breaking lower thread Thread not wound evenly on the bobbin or not drawn up correctly P.15, P.7,8
Lower thread tension too tight P.50, 51
Lint stuck in the bobbin case and inside the tension spring Remove lint and fluff
with a cleaning brush
Skipping stitches Needle not fully inserted P.18
Needle bent P.18
Size or type of needle and thread not suitable for the material P.20
Incorrect upper threading P.7
Too much oil on the machine P.44
Irregular stitches Incorrect size of needle for the material P.20
Upper thread tension too loose P.12
Incorrect lower tension P.50, 51
The material not fed
correctly Pattern selection dial not set correctly P.22
Lint stuck on the feed dog P.43
Noisy machine Check for thread in race, the slightest amount of thread in P.43
race may cause noise or binding, use material like tooth pick
or cotton swab to clean. P.52