We are doing some trouble shooting on an sq9000 in another post.
http://www.quiltingboard.com/t-47785-1.htm
BJayne notes she has cs6000 and it seems she is having the same problem as you are. She notes her solution but I don't have a visual of what she is describing. I was going to ask for more detail in case it would be helpful on the sq9000 as well.
I have the sq9000 and ex660. I was breaking needles bad. I have always zipped through a straight seam using a fast speed, lifting the presser foot, pulling the threads long enough to snip them. I have learned when I do this on these two machines I am pulling the thread out of the bobbin thread path. When I start my next stitches the bobbin thread tangles in a knot with the top thread. The bobbin can not spin so the bobbin thread pulls against the top thread bending and/or breaking the needle.
You are welcome to read the other post too in case there is something that might give you some ideas.
If you recognize your solution when you get the machine working again please will you let us know.
Regards, Dorothy