Wow nice bunch of machines! Electro grand was made by Brother. At least mine was. It has Brother stampings on the bottom and on the hand wheel.
I am not the expert Cari is on Japanese machines. I have a couple dress maker machines some I love and some not so much. One I replaced the zig zag gear when the plastic gave. You may have a plastic cam stack on that dressmaker. Read through the above stuff for more info on the camstacks. Check to see if it is cracked. Oil is your friend.