Lexmark 5070 printer broke again

i went to print a project and it was saying printer off line. i opened the front and for the 2nd time(i returned the first one) this thin, long, piece with an arrow on one end with a slit and a small slit on the other end is just hanging there. when i press the button(the check) the printer slams violently back and forth. what is this and how do i put this long strip back in and where does it go?????