Keep going to a bigger size needle. That's the only thing that stops the shredding of thread for me. One day the darn machine may want a size 100 needle and the next it may want a size 80. It's a dozen combinations that have to be pefect in order for the FMQ to be a breeze and finding that combination is the trick. Always write down the thread used, the needle used, the batting used and the fabric brand used. They all make a difference.