I bought a 301 that was like that - it was cheap. I asked the lady if she would like me to fix it or if she had her heart set on selling it. She wanted it gone. It was the feed dogs and the thumb screw for the pressure. It took a few seconds to fix that. I think someone was trying to do some free motion and never got it re-set - OR they were playing with the machine and couldn't put it back they way it needed to go. Info to fix that should be in the user manual.