Bell & Howell Filmosound 185 16mm Film Projector

Bell & Howell Filmosound 185 16mm Film Projector. Does work, powers up, bulb works, sound works. Whats neat about this piece is it has little doors to open for everything instead of the projector being exposed it stays inside, a door opens for the lens to project, the back door opens for the speaker which is removeable also. I dont know the exact year on this one so if anyone can help that would be great! It does work, the only part I cant seem to figure out is the spring coil that goes over the arm that comes out of the top, is it supposed to connect to anything to cause it to turn? Either I cant find where it attaches or the spring in the case is too large for it. I ran a reel of film through it but it was fluttering, so Im doing something wrong as I cant get a steady image, any help from film people would be welcomed. :)