HP OfficeJet 6310 Officejet Lid/Door won't close on left side?

The lid/door on my Hp 6310 Office Jet has come lose on the back left side of the printer. I can hold it down and it will print, but if I am not holding it down, the message reads, "door open". I don't know if I can repair this and if so, what type of tool do I need? Neither a Phillips screwdriver or an allan wrench worked. Thanks.