Pretty often my microwave wont heat. The thing is, it works sometimes but not others. Sometimes it will turn on, start heating, then just shut off and the screen will show F7. Other times it will finish the cook time, but the food is still cold. We will go through days where it will work just fine no problems. The one thing i did notice is when I turn it on initially i will hear some clicking noises. These are the same noises I hear when it turns off and shows F7. Is this something I can fix myself? I'm pretty handy, and have fixed my stove, washer, and dryer in the past.