The only times my Brother machines have jammed like that is when the little felt thingy behind the bobbin somehow came loose and got tangled up in the thread causing a jam. I had to glue it back down and let it dry before I could sew anymore on that machine. By the way, I have 3 Brother machines, and I had this happen on 2 of them. But if you're able to sew at all before it jams, I don't have a clue as to what could cause it.....hope you get it repaired soon, so you can enjoy your machine! I guess you can see I love mine!
Oh, I'm in no way an expert on any machine, but I am a satisfied customer.....
