I have a Kenmore 158.840. Not the same model as yours, but the same manufacturer - 158 means it was made by Jaguar/Maruzen in Japan.
The build quality of my machine is top notch, so if yours is anything like mine, you've got a keeper!
I think that the model number is the first two digits of the three digit number after the manufacturer code, so my machine is a model 84. Using this convention, you might want to search for a manual for a model 50.
Last edited by Jamesbeat; 06-08-2014 at 10:05 AM.