Good point Sunflowerzz. They're not like other machines. I can understand why there's a love/hate thing with them. They're not a very intuitive machine. You pretty much need to read the manual to understand how to operate one.
They use a 2 piece bobbin. You need to be sure the bobbin is screwed together tight. If it's even a little loose it throws the thread clearances off and you'll be fighting jams.
Rodney