I replaced my microwave with at Panasonic inverter model, it wouldn't run on a 6500 watt Onan generator. Ran fine on utility power so I swapped it for the Panasonic from the house. That one fit the width pretty well but was about 2 1/2" shorter. I cut a thin piece of steel, put a 90 degree bend in it so I had a flange about an inch wide. Painted it semigloss black which matched the microwave. Screwed it to the top of the microwave (took the cover off to find a safe place and length for the screws) and cabinet. It covers the gap and has held the microwave in the cabinet for thousands of miles and looks original.