The potted motor machines are easy to recognize. There is a squarish cap attached to the rear of the machine between the hand wheel and body.
Look at this thread: {
http://www.quiltingboard.com/vintage...r-t205360.html } This is my Model 15-91 that uses the same exact potted motor as the 201. In the first pic you can see the pot of the potted motor and it's housing on the Mdl 15.
I've put links in to Rains tutorial on how to rewire them. You'll need high speed internet to see all the pics.
My guess is your motor has bad wiring inside. Mine sure did, you can see it in the pics. But I rewired it and like I said in that thread, it's easy to do if you just follow his directions to the letter.
Joe