That is definitely a cam drive compartment. If you look at the first pic the OP posted you can see the bobbin winder in the normal place.
I'm no help in ID'ing the machine or coming up with a manual but it does use cams.
Check Shopgoodwill.com, {
http://www.shopgoodwill.com/search/s...umbs=on&page=1 }
they have lots and lots of accessories come through their auctions. If you watch all the machines that do have their cams, you might see one like yours and then you'll know what cams it takes.
Joe