Then, a couple of the spools of the Gutermann's bulky nylon starting doing something weird. About halfway through the spool, when a fair amount of the plastic at the top of the spool was exposed, it would catch on the top of the spool. If I didn't notice it and undo it with my fingers, it would pull the thread tight in the serger, then break the thread and my serging was HORRIBLE! And, it would do this literally over and over again. I finally would have to chunk the spool with half the thread still on it.
This thread was rather expensive, like close to $5 a spool, I think. So, after the second spool did this to me, I emailed the company and explained the situation and asked if there was a way I could make the spool stop doing that -- because I had tried everything. I even filed it with a nail file to smooth the plastic in case something was sticking up in it.