I have a 6600 and do a lot of machine quilting. I've got the tension thing wired now.
I learned all about tension from Cindy Needham and these two handouts really helped me:
http://www.cindyneedham.com/text/MAS...ION%202012.pdf
http://http://www.cindyneedham.com/t...ous%20Four.pdf do this one first.
When I quilt:
1. When I get those eyelashes, many times it's because the machine isn't threaded properly.
2. I never have the speed that high when I machine quilt. I have it on the lower half of the speed setting.
3. I find superior so fine 50 or bottom line in the bobbin helps, no matter what thread (any brand) I'm using in the top.
4. I keep the feed dogs up .
5. Interestingly enough, I very rarely set my top tension above 5. My machine may be adjusted differently than yours.
6. I have a blue dot bobbin case but not sure if it makes much difference.
I wish you were close by so we could put our heads together to solve this. It can get frustrating. Good luck!