That machine is very similar to my 4622a. Behind the stamped junk, the light mount, and such is a needle bar and it will have at least one set screw somewhere that when loosened will allow the needle bar to move. You've just got to get through the other stuff to get to it. Before you do that make sure the needle bar is out of adjustment. There should be two timing marks to check on the needle bar.
Be advised though most of the parts inside that area are cast from metal just a bit better but not much from pot metal.
Be careful how you work with it.
Joe