The needle threading of my Montgomery Ward 15-clone is opposite of the 15-91, and the thread path from the spool is different.
Other than that, I suppose the rest of the information would be similar enough.
Happy is the Japanese manufacturer.
RSMCO is probably for
R___
Sewing
Machine
COmpany.
I got a manual for mine, a URR-188, from
http://www.sewing-machine-manuals.com/