Edward S Fontana , CA June 30, 2017 Appliance: Whirlpool Microwave MH7140XFB1 Whirlpool Microwave Mh7140xfb1: Grill vent on microwave. How to replace Microwave Vent Grille. I had a little problem because the last person tightened the screws holding the upright supports. But I loosened them and it went right in, no problem. Do-It-Yourself Rating: Repair Time Estimate: Less than 15 minutes