As some of you know I recently posted about a thunking/clunking noise when I was doing quilting on the Brother CS6000i. After talking to a brother technician I took it to an authorized brother repair shop. Basically, she said the problem was the weight of the thread. She actually told me that the cheapest, no brand name thread worked best on this machine. After she told me that I remembered that when I bought the machine, I had several spools of old thread and just decided to piece and quilt with it to use up the old thread. Now I am sure this is the reason I didn't notice the thunking noise in the beginning. She suggested using a size 50wt and I was using a quilting thread 30wt. I still had a couple of old spools of thread laying around so I tried it and sure enough the thunking noise is hardly noticeable. It will still thunk/clunk a little with 6 or seven layers but not nearly as bad. She also said that a larger needle like a size 16 which the brother technician told me to try,would not help the situation so I am back to using a size 14 which she told me that is the only size she uses.