I have also experienced this problem, just with the first spool I used recently. Not so happy with having to mess with this!

I don't know what my machines think, but I do not like Gutterman - it has a stiffness to my touch.
I'm devoted to Aurifil and Prescencia for top thread and Bottom Line in the bobbin (it lasts forever).

I used to buy it, and have lots of it, but since I tried Connecting Threads "Essentials" cotton thread, I can really see a difference-I love the CT thread! Last night, I ran out of the color I was using, so dug into my G. and started to sew a straight seam, and noticed a bit of looping about every 5 or 6 stitches on the back, and the stitches seamed a bit wavy. I had the same needle, same tension, etc. Put another color of CT thread on, and NO problem. It sews like a dream. I am thru with G. thread. It is almost like it is slippery in the cotton fibers, and the CT thread just fits like a glove in the threads. I noticed in top stitching as well, the CT thread makes such nice smooth even stitches compared to the G. thread.

My Pfaff doesn't always like Gutermann thread. I have more problems with dark colors than light.

different machines like different threads, different threads, like different needles...it is a fine balance that only YOU can make between your machine, the needles you use and the threads!
I love Guterman, but have switched to Aurifil as more of my machines like that better!

I have also had a lot of trouble with Gutermann thread, but I didn't realise it was the thread that was causing the problems until I bought a new sewing machine. (by the way I did need a new machine). The thread in my sewing machine was getting in a knot and looking as if the tension was not right, although it had been fine until I changed thread and put the Gutermann thread in. After trying all kinds of adjustments I finally decided that my machine had broken completely and went out to buy a new machine. I transferred the thread on to my new machine and filled the bobbin up. I was devastated when my new sewing machine was showing the same symptoms as my old one. I was just about to take it back to the shop when I just thought that as one last try, that I would change the thread on top and in the bobbin. My machine worked perfectly after that! I will not be buying any more Gutermann thread again.

I truly do not like that thread. It feels like dental floss to me.