I believe you have what is considered a 15-clone. Lots of information about these machines can be found at
Will the Real 15 clone please stand up There were a lot of them made after WWII, consequently an exact age isn't available.
http://ismacs.net/singer_sewing_mach...ion-manual.pdf is one manual and another can be found at
https://www.singer.com/support I believe if you just put in 575 in the manual search box, the search results will list "W575," which will be the manual for a White 575.
Janey - Neat people never make the exciting discoveries I do.