I believe you might be right 1970s or so. It is a Badged Japanese machine. That one looks like it has a cam stack for selecting stitches. Does the stitch selector knob turn at all? Usually they are stuck. Some clean up won't hurt if it does move. Tri-flow will work wonders. You may have to put Tri-flow and then wait a couple days/weeks for the Tri-flow to work. Put the needle in the up position. You have to turn the stitch selector knob where you want the stitches then set the width and length. Some of the machines have to have some knob or lever to hold the width knob is place. It looks you might have to match the black with the black and the red with the red on the knobs. Does it have a way to set the needle left right or center? If so you can get 3 different stitch designs for each pattern. Those are fun to play with. The buttons at the bottom are for darning or not darning. Do they move? The button with the R is reverse some times those are stuck. Are the spool holders on the back? Have you tried to thread it? Here is a generic manual but it doesn't cover the cam stack/stitch selector knob. It will thread the same and wind the bobbin the same. It just won't help with the stitch selector. Keep the needle up when you move the knobs.
http://www.dontai.com/wp/images/imperial-535-manual.pdf