Lexmark 6500 Series printer: printer screen says " cover open" when not so?

There should be a plastic piece protruding from the cover that goes into a hole in the main body, this operates a switch to tell the printer that the cover is closed or open. Make sure it's not broken off or, take the printer apart and find the switch, it will be small with a spring operated arm on it. Either bypass the switch by cutting the wires and twisting them together or adjust the switch forward slightly. You could also check that the hinge you mention isn't broken as it sounds like there is some slack in the adjustment.

Paul.
September 2013