Nylon gears last up to 35 years or longer, Miriam. Once replaced, they're good to go for another 35 years. If you're scared to use them, send them to me:> I own a vintage Bernina 830 and many vintage Elnas. A few have a nylon gear or two and I certainly don't consider them plastic machines. This model, Lydia, was prone to problems. One model machine is not representative of all Necchi machines.