I have a Nolting and have had several models. Tension is a big thing. My dealer, Joyce, has written on it,
http://delightful-qs.com/blog1/2017/...g-the-tension/. She is very helpful. I have tension issues at times. Here are some first things to do:
Buy a Towa gauge for your bobbin. It is worth it. Then you are just fiddling with the top thread.
Scrupulously check to see if your frame is 100% level.
Slow down on curves.
Contact Joyce.
Check how the bobbin winder is winding the thread-evenly, tight tension.
Make sure your thread is good. I use Glide on the top, Omni or PremoSoft in the bobbin.
Make sure your quilt is loose in frame and not drum tight. This helped me immensely. I float my top. If your quilt is too tight in the frame, the fabric has no give, especially on curves.
If you have questions, private message me.
Linda