I believe it is a Singer 404. You need to check your hinge pins. It look like only the front one is holding. That's a lot of a machine to have falling in your lap. With a helper, tilt the machine back and look at eh front hinge and see the set screw that holds the hinge arm. you may need to loosen it to get the back one in place. Hope it is there. Lots of love for those early slantnose machines.