I have quite a few vintage machines with nylon gears. There is nothing wrong with nylon gears if they are in good shape, or if easily replaced. If it is a machine you want or are very interested in sometimes the gears or cam stack gears are worth being replaced.
My husband purchased a Pfaff 1222 because of all of the neat things it does, he loved the look of it, the feel of it, etc, and it is very very well made and uniquely designed into a small narrow space.
It has a small hairline crack in one of the design cams which is not a problem. It is still in very good sewing working condition. He repaired the machine which needed some major repairs and it sews perfectly. If the nylon cam cracks further or causes sewing problems he will replace it by ordering a new one. But for now the old one still works fine.
He gets a real kick using this machine and it is fun for him. As with san-sing, it has some unique features that makes it a fun to use and collectible keeper.
I guess what I am trying to say is don't discount machines just because they have nylon gears. They lasted many many years for the most part and maybe would have lasted longer if the machines hadn't been stored in a garage, shed or barn or abused. Take a bright flashlight and check out any nylon parts, if they pass inspection don't be afraid to buy it. JMHO
Now that our Pfaff 1222 purchased out of a cold/extreme hot storage unit where it sat for 11 YEARS!!! is in a nice controlled temperature home, all cleaned up and repaired we fully expect her to sew well for us for another 50 years. ( She will out live us at that point!
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