XT not cutting bobbin thread

[Wishes]

We have an XT that is about three years old. It has this moment after about 8 designs that it chooses not to cut the bobbin thread. It cuts all theads during the design sewout but on the last thread cut it fails to cut the bobbin thread. As you pull it out a trail of thread follows you. Each time we take off the needleplate, clean everything, send out the knife and the selector, blow things out, check for anything amiss and nothing. Put it back together and it works for about 8-10 designs and it happens all over again. This same machine also fails to catch the bobbin thread often. We do all the maintaintence and follow all the procedures. Is it possible that these two things are related or am I dealing with two different problems? Any suggestions?
Margaret

[jason wright]

I had the same problem. the tech support said is was the bobbin tension was too loose. I tightened the tension on the bobbin case and it fixed the problem.