The issue with plastic gears have been up for discussion before, but I can't find the posts. I think there have turned up both all metal machines and with plastic gears with the same model number. For the later models 600 numers and up it seems we have to check the machine individally. Some plastics have lasted better than others too, that's a factor to be considered. In some cases there are both plastic and metal gear replacements available. I'm not too strict on plastic parts, since my favorite zigzagger has a few.