Singer HEAVY DUTY 4423 Manual page 27

Problem
Seams gather or 1. The needle is too thick for the fabric.
pucker 2. The stitch length is adjusted wrong.
3. The thread tension is too tight.
Uneven stitches, 1. Poor quality thread.
uneven feed 2. The bobbin case is threaded wrong.
3. Fabric has been pulled.
The machine is 1. Lint or oil have collected on the hook
noisy or needle bar.
2. The needle is damaged.
The machine Thread is caught in the hook, because
jams upper tension is not threaded correctly.
Cause
1. Select a finer needle.
2. Readjust the stitch length.
3. Loosen the thread tension.
1. Select a better quality thread.
2. Remove bobbin case, thread and insert
correctly.
3. Do not pull on the fabric while sewing,
let the feed dogs pull the fabric under the
foot.
1. Clean the hook and feed dog as
described.
2. Replace the needle.
Remove the upper thread and bobbin case.
Gently rock the handwheel backwards and
forwards by hand and remove the thread
from the bobbin area.
Correction
27