I use isocord thread. Have been using it for a couple years with no problems until lately. Last quilt broke threads really bad so i made a large piece of fabric with backing batting and used the fabric for top. i ran the machine fast and slow . made circles on fabric .It didn't miss a stitch or break a thread . sewed a beautiful stitch I have changed needle twice cleaned machine. It was serviced about three months ago. i also loosened the tension on the top thread.

I use a size 18 needle for FMQ and I try to use a finer thread in the bobbin. For me this combination has produced the best results for me. Thicker threads on the top will cause skipped stitches for me on curves so I do not buy them anymore. Good luck!

clean it out good every time before you start 'quilting'. and use the same thread top and bottom. I was having trouble one time, and changed needles, and ran the thread thru both loops of first top, tall, silver thread guide. must have been holding my mouth right then, because it started working..
But #1......clean it good before you start quilting a quilt......

my needle is a Schmetz HLx5 high speed. that is all it says on the package.

i am doing a pantograph on a little Grace 2 frame.

Ah ha! If you're on a Little Gracie frame, is your fabric stretched too tight? You don't want it to be a trampoline. And is the quilt surface level instead of angled? I agree with the others about using a larger needle. Below where it says Schmetz HLx5, it should say a size like 80/12 or 90/14 or 100/16. You probably want the 100/16.

The zig-zag test is a great way to test if the timing is off.

Good Luck with your quilting!

Skipped stitches means the threads are not locking...bobbin and spool thread. This is usually caused by the needle not matching your thread.....always use a 90/14 top stitch needle when quilting. The larger eye allows the thread and needle to get down to the bobbin thread easier...thus no skipping. Let us know what works for you, there are a lot of Janome owners out there. I have five.

I agree. This week I wanted to sew on my red eye Singer, threaded it with Superior thread and all I could get were nests on the back side. Tried setting the tension and several other options. I know that when I last sewed on it, it worked fine. Finally I put the Connecting Thread back in and it sewed great. Certain machines like certain threads. Made a believer out of me.Sharon

I had this problem with my Janome and it was most frustrating. What it turned out to be was the fabric/needle combination. I was sewing with batiks and there was one blue batik where this was happening. I changed my needle to a sharp so that it was piercing the fabric better - prior was using a universal which had a duller point - and that took care of the problem. Because of that I rarely use universal needles anymore and just stick with a topstitch or sharp which both have a sharper point. Top stitch has a larger eye on it.
I also occasionally have skipped stitches when I am sewing over bulky seams too. Look to see if there is any pattern to where the skipped stitches are. A particular fabric, seam etc. That might help narrow down the problem

I'd make sure you're threading the machine properly per the book.