In the ISMACS Comprehensive Singer Model List: {
http://www.ismacs.net/singer_sewing_...ist/index.html }
It lists the motor family for many of the electric machines. Such as for the 15-97 it uses the "B.R." motor. If ISMACS has this info listed for your machine you can at least tell if the motor is of the correct motor family. I have several Singers that came to me with motors other than what ISMACS says should be there, so some may have been switched out or replaced.
Joe