Yes, the compartment is for cams. Unfortunately, finding the right cams might be like looking for a needle in a haystack. Your Japanese "badged" machine probably has several different names as they were sent out with different names to different retailers. If the other example you found has pictures of its cams, that would be the most telling as to what cams to search for. There are many different cams, with different sizes of holes and even number of pins that turn them. You probably have to try them on to see if they actually fit.
There is a yahoo group called vintagejapansewingmachines that has many pictures where you might find other examples. They also have some generic zigzag manuals for download. You do have to have a yahoo ID to join, but that is free to sign up.
Usually, they're very good machines.
Good luck.
John