After just 1.5 years - just outside the warranty period, of course - we're having the same issue with sparks and burning components that other customers have reported.  All of the issues appear to be happening at the same point in the microwave, in the back corners where the drawer rollers rest against the interior when the door is closed.  This is clearly a design or manufacturing defect.  And now we have to pay out of pocket to repair or replace an expensive, relatively new microwave.