There are several threads about 15 clone machines. One of which is
Will the Real 15 clone please stand up A generic manual for a 15-clone machine can be found at
http://ismacs.net/singer_sewing_mach...ion-manual.pdf
Most of the Kenmore machines will have a number like 117.28 or 148.231 or 158.1941 The number before the period punctuation mark indicate who actually manufactured them. I'm curious as to which one yours has. I know there is a Canadian sold 15-clone with the model number of C877.15
Actually, the Singer 15s and pretty sure most of the 15-clones do have a hole on the right back side of the light. It seems like I have seen
just one Japanese 15-clones that did have a cover for it, but don't remember the badge name. The inspection plate is on the back left side of the machine and it looks like yours is there. It allows you to get into the top of the pillar to oil some parts in there that are difficult to reach any other way.
I hope you can find a tension assembly as these generally are very good straight stitch machines and is favored for FMQ.
Janey - Neat people never make the exciting discoveries I do.