Presser foot pressure wrong

A needle that clicks against the plate or skips stitches is often bent from nicking a pin or age. Replace it immediately, since a bent needle can also throw off hook timing.

Fabric pulled down into the needle plate at the start of a seam happens when feed dogs grab thin fabric before the stitch locks. Start on a scrap leader and hold both threads taut behind the foot.

A machine that locks up, often with a knot of thread underneath, usually means the bobbin is threaded backward or wound around the case. Clear the jam by hand, rewind the bobbin, and rethread from scratch.

Skipped stitches on knit fabric happen when the needle pushes fabric down into the plate hole instead of piercing it, usually from a sharp needle or overly stretched fabric. Switch to a ballpoint needle and support the fabric.

A snapped needle usually means fabric was pulled while sewing, a pin was hit, or the needle was too fine for the fabric. Slow down, clear pins from the stitch path, and size up the needle.