Well, all I know is that the parts wear out faster on the newer machines. I just had to have the feed dogs replaced on my embroidery machine. Can you imagine wearing out the feed dogs?????? I've been sewing since I was knee high to a grasshopper (55+years) and have many sewing friends and no one has ever had to have their feed dogs replaced. Even tho, am glad to have the machine cleaned and back to me.

Were the feed dogs a plastic or a rubber compound? I know some of the touch and throws are that way (rubber) so they can do the side to side motion for the flexi-stitches and they wear out. They wear extra fast if you get oil on them while oiling the bobbin area too.

I'm not sure if the feed dogs were plastic or a rubber compound. He showed me the ziploc bag with the old ones in it and thought he put them in my sewing machine bag, but when I got home, they weren't there. My machine doesn't get oiled (by me) anywhere as it is a self lubricating machine, so I know I didn't get any oil anywhere. I figured that the side to side motion embroidery is the main cause of them wearing out, but frustrating anyway.

I've had to replace metal feed dogs on vintage machines. It happens. Sometimes the teeth are chipped off and just don't grab like they're supposed to.