Try tightening the tension. Mine is a jenome, but the tension goes from 1 to 9, 1 being tightest.
Make sure you have no threads tangled underneath in the bobbin case. If I din't pull it all out & check it'll usually just tangle instead of just being loose.
Another thing to try is adjusting the foot. Mine will be loose if the foot isn't down far enough. (On mine the adjuster thing is a knob at the top of the machine.)