Singer 603 bobbin conversion
 

I have a singer 603. I love the machine except the self winding bobbin. Is it possible to pull out the hook and turn this into a 403? What work would need to be done. What parts would I need to find. I don’t mind using an external bobbin winder.

I'm not much of a mechanic, but I don't think that's possible. The two machines have totally different bobbins. The bobbin for the 603 doesn't have a hole in it, which makes free-standing bobbin winders unworkable. Every scenario I can visualize wouldn't work for the same reason.

The bobbin for the 403 (66 style) wouldn't fit in the bobbin case, either. The whole bobbin area would have to be replaced, which might be possible, but it would take a lot more machine knowledge than most mechanics, even really good ones, have.

bkay