Hi - On the Singer website there is a place to find the replacement parts for your machine, including the bobbins. You have to look hard to find it, but it's there. Your 201 machine takes a Class 66 bobbin. Best to stay with metal bobbins in the older machines. The plastic ones don't seem to work well at all. Lots of people here have tried them and they're not good in our older girls. You can get metal reproduction ones that work fine.