I was quilting with my longarm on a Christmas present for my son and I was almost finished (and things were going so smoothly....I just knew it was too good to be true!) when I was starting to take it off the frame I notice that the back stitching about 18 inches deep to go on the quilt was all loose underneath.......I had to take it all out. It started when I changed the bobbin. I should have paid more attention to it like I did the rest of the quilt as I was working, but figured it was going so smooth that it would stay that way. But...........when I changed the bobbin I hesitated with it because it didn't seem like it was wound the same as the others. Boy was that a huge mistake. Cost me alot of time too!! So after taking it out and winding more bobbins I had not one problem finishing it. So when mine happened it was the winding of the bobbin that made the difference.
I also have been sewing before and when the bobbin was getting low, the stitching was not the same. I could tell when it got to that point. Also I have gotten thread that twists when you sew and that makes it break or not sew right. I have had to dispose of some thread because of it.
Barb