Were the bobbins your friend sold you with the machines empty or ones she prewound? If she prewound them, the winding tension may have been off. To check, take a small flat object (like a screwdriver) and push against the thread. Is it squishy? If so, the thread was wound too loosely and will give the problems you describe. HQ has an instructional video on how to use the bobbin winder and check the tension. Good luck. I know from personal experience how frustrating it can be to just want to play with your baby and end up having problems.