Shut off power to your Kenmore microwave by flipping the breaker at the household breaker panel.
Remove the two screws from the vent cover on the top front of the microwave with a screwdriver.
Pull the vent cover forward then lift it completely off of the microwave. You can now make any repairs within the ventilation system.
Check the vent cover for cracks or other damage to see if it needs to be replaced. Wash the vent cover, if necessary, with warm, soapy water then wipe it dry with a towel.