I am not sure how old my range/Oven is but as it was in the house when me and my wife purchases it. The problem i am having is the oven will not turn off. It doesn't feel like its getting to peak temperture but staying around 400 which is what i last had it when I cooked. The model number is FEF355A, it is a frigidaire, any help would be grateful as i dont know much about appliances but can do repairs and such on my own.