Brother International T-8752C Instruction Manual - English - Page 86

14. TROUBLESHOOTING Problem 5 Uneven seam Possible cause y Is the presser foot pressure too weak? Adjust the presser foot pressure. y Is the feed dog too low? Adjust the feed dog height. y Is the bobbin scratched? If the bobbin is damaged, smooth it with an oiled grindstone or replace it. 2948M 6 Large degree of puckering (excess tension) 2949M y Is the upper thread tension too strong? Make the upper thread tension as weak as possible. y Is the lower thread tension too strong? Make the lower thread tension as weak as possible. y Are the thread take-up spring tensions too strong? Make the thread take-up spring tension as weak as possible. y Is the thread take-up spring operating range too large? Move the stopper to as high a position as possible. y Is the presser foot pressure too strong? Adjust the presser foot pressure. y Is the sewing speed too fast? Use the sewing speed control keys to gradually reduce the sewing speed. y Is the thread take-up amount too small? Adjust the thread take-up amount. 7 Material slippage y Is the presser foot pressure too strong? Adjust the presser foot pressure. Page 52 73* 51 51 66* 65* 52 28 54 52 2950M 8 Lower thread is tangled at y Is the bobbin spinning direction correct when the lower thread is the sewing start. being pulled? Spinning of bobbin during thread trimming Set the bobbin so that it turns in the opposite direction to the rotary hook. y Is there too much thread Lower thread wound onto the bobbin? The bobbin winding amount should not be more that 80 %. y Is the anti-spin spring attached? (Models with thread trimmer) Attach the anti-spin spring. y Is the bobbin turning smoothly? If the bobbin is not turning smoothly, replace the bobbin. y Is a bobbin other that the light-alloy bobbins specified by Brother being used? Use only bobbins which are specified by Brother. 2951M 2124M 21 • 22 20 21 • 22 21 • 22 77 T-8421C, 8422C, 8452C, 8722C, 8752C