Recipe for Thread Jam
What I like least about Singer Featherweight is having to take that bobbin area apart every time my 89 year old Mom jams hers up and tries to fix it herself. Try oil and the hemostats first to get the thread out. Take it apart if necessary. There are plenty of tutorials how to do that.... Start a new thread about your thread jam and someone will help you figure it out... better still there is a little box at the top of this very screen that says search - see it - it's on the upper right - type in 'thread jam' and you might find an existing thread that tells how to fix/unjam your mess with out waiting for someone to reply...
BUT the best thing you can do is prevent thread jams in the first place and this is true of your vintage machines as well as a Featherweight or Singer 301:
Make sure the bobbin and top thread are not engaged in the bobbin hook when you start, stop, or move your fabric around by turning the balance wheel toward you and making sure the thread take up lever is all the way to the top.
Even if the needle is up all the way there can still be thread caught around the bobbin hook. The top thread needs to make it's loop ALL the way around the bobbin or it will be caught in the hook and that is what makes it jam. See that the needle thread is pulled straight back with out crossing or looping in the needle area (I repeat: thread take up lever all the way up)
This is how it should NOT look:
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The thread should be separated. Bobbin thread out the bobbin hole and top thread out the needle - not crossing and not coming out of the hole.
In my picture, you will notice that the needle IS up but the top thread is still in the hook - see needle hole.... Can you see that the take up lever is NOT all the way to the top? I tried to draw arrows but the computer didn't like it... I crashed the paint program.... I do not give computer advice ever... never ever. turn it on. if it works you are ok.
Only turn the balance wheel toward you turning it the other way can make thread jam....
Keep your tension well adjusted so you don't get big loops on the under side.
Make sure the long thread tails - bobbin thread especially never get in the way and go down into the bobbin area - clip after a few stitches and discard the thread tails. Some people chain a leader or ender piece at the beginning and end of each project to prevent tails and keeps the jams from happening. That said you still have to make sure the take up lever is up, the top and bobbin thread aren't crossed or it will still jam as soon as you start to sew even with a leader or ender piece.
NEVER LET A SEWING MACHINE KNOW YOU ARE IN A HURRY.....
You should be able to prevent a lot of thread jams. If you still have a lot of trouble I would recommend a refurbished Singer 15 or a 15 clone, while heavy and not as cute, those rarely jam, if they do they are easy to un-jam and they make a quality stitch. There are hundreds of other brands and type machines that don't jam as easy as a Featherweight or a Singer 301 and they may be better suited to you.