My New Home wonderful sewing machine from the 1970's had the plastic gears wear out too. I had never used that machine much as I was not a sewist, just a hemmer of everything I bought. I loved that machine, but plastic gears get old, dry out and break even if not used much. Everything else was metal in that sewing machine. For this reason I won't buy old sewing machines, because I don't really know what I am doing, and don't want something that is ready to break apart.