Sewing Machine La Salle

I have a sewing machine and I want to know, if it's possible, the year of fabrication and please ?
The color of the machine is a sort of blue.
The inscription on the top is :
La Salle Precision Manufactured Sewing Machine
The numbers graved under is :
A/12 7982 F or maybe A/I2 7982 F (because I'm not sure to read it correctly)
The serial number of the motor is :
121157
I hope that you will be able to tell me this information.
Thanks a lot!