Originally Posted by
Lady Diana
DO not mess with your tension. Check the thread path, bobbin holder for Knicks and dings, match your needle size to the thread you are using. I always use a 90/14 organ topstitch needle for 40 and 50 wt. Thread.
make sure your tension disc's are clean, I hope you learn what is causing this....I know it's very frustrating.
Are you talking about on a longarm (not messing with the tension)? OP is asking about a longarm - the Kathy Quilts/Grace Company machines.
Fine tuning tension, bobbin first, then upper thread to match, was one of the first things my longarm instructor and my longarm dealer taught me to do. I check and adjust (if needed) bobbin tension on every bobbin and check top tension with every bobbin or start of a quilting session (if I haven't finished a bobbin from the previous day).
Most longarms use 16 or 18 longarm needles, not smaller topstitch ones. Bernina's Q-series might be the only one that uses domestic needles.