The range has a red light that has come on in the front upper left, and at the same time the two left burners no longer work- no gas and no spark. The right two burners still work fine. I cannot figure out how to get into the left section of the oven, under the burners. The right side is easy, it can be accessed just by removing the grill. I don't know if I even to get into that area, however. Any idea what is going on? Thanks