I have a 6600 and I love the tread cutter, but once in a while the thread jumps out of the tension take up leaver when I remember I twist it the opposite way on the lever. Some of the times the thread comes out of the needle, I have to retread it, thank God for the thread cutter. With my Baby Lock Ellangant 2 the thread cutter works fairly well. If the tension is not thight on the top thread it does not work the best. I agree the machines get really dirty fast . I wonder if it is the material now a days or the threads?