You already have the manual info. Class 66 bobbins and regular old 15x1 needles. The bottom is covered. You can pop the two round covers off to grease the gears. It's a gear driven full rotary hook machine kind of like the Singer 201. The screw above the Singer badge holds the motor on.
To me they're a neat design. They were Singer's first electric only sewing machine. Singer didn't make them very many years, I suspect due to manufacturing cost and it really didn't do anything better than Singer's other designs like the 66.
Rodney
I gave mine to my daughter. It makes a really pretty straight stitch.