Originally Posted by
Mickey2
Is the bobbin case on the 401 and the 503 similar enough?
They seem to be identical to me. I only have the 401 and the two 503s, but the "innards" appear to be same. Of course, the 401 has the built in cam stack and the 503s only have removable cams. Other than that, the differences appear to be just cosmetic to me. I'm no expert, though.
bkay