I have trouble too with sewing machine and my sewing pal says you have to have really good thread and bobbin. No dust in bobbin case, dust every time you start. This helps a lot. Then on embroidery machines it the same only more so. Now the last one is who made your design it how well your digitizer made the product. May have it to tight or loose at times she said you may even have a blank space or too stiches in one spot.