Ileen,
The Singer 413 is your basic SS / ZZ machine. It will do some stretch stitches. It does not use cams. This model was made from 1972 to 1973.
It's a decent machine with the body made from cast aluminum ( not heavy at all compared to a cast iron machine ).
They use low shank feet and attachments, regular 15x1 needles and either the metal or plastic Class 66 bobbins. The bobbins depends on the bobbin case. Metal to metal, plastic to plastic.
Manuals can be had from: {
http://www.singerco.com/accessories/instruction-manuals }
It does have one weakness and that is vertical shaft top gear. It's plastic and they have a tendency to break. I've had two of these machines, and both of them broke that gear. Considering they are over 40 years old, it's not really that surprising.
The gears can be had and they are not terribly expensive or hard to replace.
Joe