Using improper needle, thread or the fabric prepared insufficiently for embroidering.
Use a ball point needle 75/11 for embroidery.
Use embroidery thread and embroidery bobbin thread.
Attach a stabilizer material for embroidery to the fabric.
Upper thread tension is too tight.
Adjust the thread tension.
Fabric is pulled during embroidering.
Do not pull the fabric during embroidering.
Fabric is pulled during sewing.
Do not pull the fabric during sewing.
Spool cap is set incorrectly.
Check the method for attaching the spool cap, then reattach the spool cap.
Refer to How do I thread my machine ?
There are scratches around the opening in the embroidery foot.
Replace the embroidery foot, or consult your authorized Brother dealer.
There are scratches on the bobbin case.
Replace the bobbin case, or consult your authorized Brother dealer.