I have class 15 Singer, looks like yours. They came in a cabinet that's why it looks like it has no sturdy bottom. I found the manual online, it's the manual that is used for most all the vintage Singers. If all the parts are there and the motor is okay, it will be a great machine to have. There are some great websites on restoring and maintaining old Singers. Parts are easy to find for them and not very expensive. I paid $150 for my Singer, excellent condition and in nice wood cabinet.
Here is picture of mine in use by my niece.
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