I mainly sew with a Singer 403A and dearly love it - I have forsaken a Viking and a Janome for it
My sister sews with a 401A - she gave up a perfectly good Kenmore for it.
We each got our granddaughters a 404a to learn on.
These machines all have the same bobbin case which rides on the shuttle. I think it is a good feature of those sewing machines because if you get a bit of thread tangled you can pull the bobbin case out and the tangle comes right out. Then put it right back in. However it can be a chore to get it back in if you don't know how. My sister and I both learned to take it out and put it in through trial and error. One GD is 7 years old. She does not live near by. One of the things we taught her was to take the bobbin case out of the shuttle and put it back in. We did it over and over until she is good at it. It is simple enough once you know how. There is a grove piece on the bobbin case. First I line it up with the part that sticks out on the shuttle. (It is near where the needle goes.) Then slide/drop the bobbin case into the shuttle - the bobbin case rides on/in that rim - there is a black spring part on the right that snaps in and holds it in place. Sometimes it takes a try or two to get it in but usually it will go right in if you line up the notch and remember the bobbin case 'rides' in/on the shuttle. If that spring piece doesn't snap right in just so take the bobbin case back out and try again. Some times it takes more than one try. There should be a picture of it in the manual or maybe on line - that might help. It is something you may want to practice doing until you get it down easy.
here is a link that may help
http://www.tandtrepair.com/SlantOMatics.html and look at bobbin case removal
I know I'm adding on to a very old post however this is probably the hard part about any Singer 401, 403, 404, 500 or 503 machine. Once you catch on it is really very simple. I hope you got it figured out - those are wonderful machines.
Help With Singer 403A Bobbin Case
