my microwave has two bulbs located on the roof of the inside of the microwave. the bulb on the left is a halogen bulb, 1000 watt, the bulb on the right is a 500 watt quartz bulb that burned out. I thi k it's the grilling bulb. there is a cage over the two bulbs which I cannot remove, no screws on the cage itself and it doesn't come off. how do I replace the quartz bulb ? thank you