I, too had this problem with my Janome 7700 Memory Craft. After multiple cleanings and needle changes I learned that 'thread delivery' played a key part in even and unbroken stitches. If your spool is stack wound, it must stand upright so thread comes off the spool horizontally, preventing twists. It simply unwinds. If the thread is cross-wound on the spool, it should deliver off the end of the spool. My machine has the capability of both deliveries. I simply use the bobbin spindle for stand-wound spools. There are several different spool holder stands on the market that can help this issue too. Also, some threads have a very slippery surface. Increase top tension for these. Hope this helps.

Have you used this machine on a frame before? Because frame quilting requires different tension settings from sit-down quilting. If you have not yet tried it, I recommend following the instructions in this Jamie Wallen Youtube video (applies to domestic machines as well as longarms when frame quilting):
https://www.youtube.com/watch?v=Q1mRhcquZTM

I don't have any suggestions not listed above, except to try using a thread stand and/or thread net. My Janome 1600p has another funny little quirk. If I hit the gas too hard when beginning, the thread can jump out of the thread path, wrap around the guide between the tension discs and the take up lever the wrong way, and break--hard. It broke a titanium needle a while ago.

yes i have always used this frame.

I had a similar issue with my Janome 7700. I was using old thread and and universal needle on batiques, that was my issue. So I would say:

1) Try a needle from a different pack incase it was a quality control issue on the run of needles.
2) Try a different thread
3) If you have leftover fabric, put together a little practice sandwich and see if you are having the same issue. If you don't, compare what is different between the two.

Hope that helps. I know these issues can be so frustrating when you are on a deadline.

I had the same problem with my Janome 8900. The dealer recommended Janome purple tipped needles, size 14. It solved the problem.

Thanks so much for this tip. I didn't realize these needles existed. I will give them a try as I occasionally have skipped stitches with my 8900

granmasharon, your problem was not the thread and machine, it was your thread and needle combination. Changing the needle would have helped your problem.

My Janome kept skipping stitches and making uneven stitches. I tried working in the tension forever, it seemed. Then I changed the needle, which helped some. I discovered that my machine is extremely sensitive to lint around the bobbin. I clean it out constantly now, which is a pain. But now the stitches are back to normal.

I use the bobbin case with the blue dot when fmq'ing; makes a big difference.