I can almost guarantee that the clunk you're hearing is from the black energy chain that houses the ink lines rubbing on the inside of the chassis cover at the top. Press and hold the INK button for 3 seconds and physically watch the head move left and right.
The aluminium bracket that holds the energy chain to head carriage cover opens up and becomes loose after time causing the chain to sit back.
The aluminium bracket that holds the energy chain to head carriage cover opens up and becomes loose after time causing the chain to sit back.