Why does my machine jam at the start of every seam?

Three habits cause almost all start-of-seam jams, and all three are easy to change.

Starting at the very edge of the fabric. The feed dogs have nothing to grip, so the fabric does not move while the needle keeps stitching. The thread piles underneath. Start three or four millimetres in and reverse back to the edge, or begin on a small scrap of fabric and run straight onto the piece.

Not holding the thread tails. With both tails loose, the first stitch can pull the top thread down into the bobbin area instead of forming a loop. Hold both gently behind the presser foot for the first few stitches.

Take-up lever not at the top when you started. No slack for the first stitch. Turn the handwheel towards you until the lever is at its highest before you begin.

Then the two structural checks. Re-thread with the presser foot up, so the thread is genuinely between the tension discs. And clean the bobbin race, because a partial jam there shows up first at the start of a seam when the hook is under least load.

A leader scrap — a folded offcut you always start on — solves the first and second at once, and costs nothing.