SINGER CE-150 Futura - Manual (Page 115)

SAFTY DEVICE
ACTIVATED
Machine is locked up due to thread entangled with bobbin
case or rotation interrupted forcibly.
4 Turn off power switch and eliminate the problem that
caused the machine to stop.
Bobbin winder is moved to right (operating position) during
sewing.
4 Check bobbin winder and move it to left.
Small hoop is attached when design for large hoop is transmitted.
4 Turn off power switch and attach large hoop.
Check cable and power switch.
4 Check that USB cable is connected and power switch is
turned on.
Bobbin winder is in operation.