I ask my tech about the magnets as I have an embroidery machine. He said the magnets that are used for pins and needles and the magnet bowls mechanics use are not strong enough to hurt the machiness. They use to say don't vacuum
near your machines another wife tale. I have used my magnetic pin cushions for 5 years haven't had a problem. But if it worried me I definatley would not use them. Peace of mind is worth a lot.