Silly question - how does one use a thread net?
I had shredding with my Brother P1500 and it turned out to be the hook. I traded it in on a new same machine and I don't have any of those issues anymore. But, suggested to me were as above, changing needle, going up a size, don't pull the quilt, and one other one is put the spool far away from the machine through a thread stand. On the old machine all that helped, but, didn't solve the problem. Good luck, let us know what worked.