I'm not sure changing the needle would help the OP as she stated the shredding was happening way before the thread hit the needle's eye at the thread guides before the needle. I don't know if this will help but I had this happen to me on the LA with a poly thread from Superior and I needed to really loosen up the tension on both top and bottom. If changing the needles doesn't help she could attempt loosening the tension on both top and bobbin.

I've had this happen with my 6600 just this week. Glad to read it might be the thread, I was using Bottom Line which I think is poly/cotton. I'll have to try loosening the tension.

Thanks for asking the question!

My Janome sometimes gets picky about the thread, I found out that she likes it better when both the threads match. That is on straight stitching. I think maybe when fmq, the cotton thread gives a bit more. Just a thought.

Thanks for all the suggestions....will be trying them to find a solution, but not this weekend as am house and dog sitting for DD.