If you contact Lexmark, they can send you a check list, which provides a route if the printer mechanics are faulty.Very easy and simple to do.
On the USB connection, is this via a self-powered hub or multi port hub or is the connection straight into the computer socket.Lexmark state, that it must be a direct connection into the computer.I had this problem with my Lexmark X85 and X5150, and after transfering to a direct connection, most of my communication problems were solved.
Contacting Lexmark by telephone can be an 'on-hold' delay situation, so be prepared, and select a good time span. Contacting by email or fax, can also have problems.As they have had some recent 'lost' emails situation.I found the email service is either fast response or very slow, to the point of non answer. Taking the machine back to Staples,will possibly result in a replacement [if they have stocks]. Which may still not solve your problem, unless you contact Lexmark.
Sorry to sound gloomy, but I went through the try this, try that situation. Eventually all turned out okay.