Oven is 9 years old. Stopped heating and started making a noise unheard before. Noise is a clicking sound for about 3 seconds, recurring about every 15 seconds after start until set cooking time ends. Internet research says faulty magnetron, capacitor, or diode. All 3 have been replaced with factory parts to no avail. Other fuses or temp sensors at fault? I am a DIY type guy, this oven is expensive to replace, hence my efforts. And, I do discharge the capacitor before working on it. I can't accept defeat! Suggestions please, and thank you in advance for your help.