Machine skips stitches and the skip stitches make loops.

SOURCE: Skipped stitches & looping on the bottom of Quilt

Try a different needle. Use a quilting or topstitch or even a metallic needle - one that has a larger scarf than normal. The scarf is the groove at the back of the needle where the thread goes while the stitch is being formed. Quilting threads often need more "room" there. I have been told that the Inspira quilting needles are good because they have a thread groove on the front and the back of the needle. Not tried them personally but might be worthwhile for you to consider.

For the looping, you could fiddle with your tensions a little either loosening the bobbin tension or tightening the top, or both. Only ever do this in very small increments. But the good news is that even the "professional" quilters do not have perfect quilt backs - just have a look at them at quilt shows!
Pam M.

SOURCE: I HAVE A BROTHER LS-2125 SEWING MACHINE AND THE

Sounds like either the bobbin case tension is too light or is not in the tension at all.

Consult your manual for how to place the thread in the tension and retry. Increase the bobbin case tension if necessary.

The top tension may be set too high.

SOURCE: my new babylock is skipping stitches while sewing

try using a heavy needle like a 90/14 sharp or 100/16 sharp and replace it often while doing thicker materials

SOURCE: skipped stitches

Change the needle first and make sure it is inserted correctly. Use good thread i.e.: Guterman or Metler are some. If you are using a stretch material then put a stretch needle in the machine. If you do all this and it still skips then you may have a mechanical problem with the machine. The machine is "out of timing". Have a good tech. look at it. This happens quite frequently on "inexpensive" machines. Sorry.

SOURCE: my brother sewing machine, My

check needle to see if it's damaged-roll on flat surface to see if it roll correctly
adjust top & bottom tension according to operation manual