still pulling. The fabric is cotton gingham check. Should I use another wt of bobbin thread?

Meganne gave you a great answer. I generally don't use heavier weight bobbin thread, unless I'm doing FSL I want to be double sided, then I use the same thread in top and bobbin. Obviously it wouldn't matter if it came to the top or not, that way. Make sure your top tension is loose enough, and make sure that bobbin is caught all the way into its tensioners. That can cause all kinds of problems, even if it looks right. Take it out and do it again, just to be sure. Let us know how you make out! Hugs, Marji

Which tension are you changing, the needle or the bobbin?

I would first double check to make sure your bobbin thread is actually caught correctly in the bobbin tension spring.

Then I would try loosening the needle tension.

If that didn't work I would adjust the bobbin tension.

Each time you make an adjustment write it down so you can reverse it later.

I use 90 weight bobbin thread and have never have any problems with it.

If all else fails chuck the new thread and go back to your old one, your machine just may not like it, or it may not like the brand.

Good luck and please let us know if you solve your problem.
hugs n roses, Meganne