I've used a 40 wt. varigated YLI machine quilting thread on the spool to FMQ on my Bernina. I had a hard time getting the thread to not pull to the back. I made a loooot of sandwich samples before I got it right. I did find that it also made a little thread ball at the needle so I changed to a slightly bigger eye and managed to finish. I will not use that brand again. On a longarm can you adjust the bobbin tension a little looser so that there is less pull on the top thread? Other then changing your needle and fiddling with the tension, I don't know what else to try other than changing thread. Bummer!