As with any electrical appliance, making sure your microwave is working properly saves time and money. Since a microwave uses electromagnetic radiation when heating food, it is also important to make sure your microwave seals and works properly to avoid possible radiation exposure.
Look at the paperwork that came with your microwave when you purchased it and determine how old it is. If you don't have the paperwork, look on the back of the microwave and find the serial number. Call the manufacturer and get the date your microwave was manufactured. Delish states that a microwave generally lasts for 10 years before needing to be replaced. Therefore, if your microwave is older than 10 years old, it most likely needs replacing.
Check the seal around your microwave's door. If it is cracked, broken or shows signs of ware, replace your microwave. According to the Food and Drug Administration's Center for Devices and Radiological Health, a faulty seal allows radiation to leak and may cause exposure to you and your family.
Review the cooking chart located in the Resources section for your microwave. If it takes longer than recommended to heat water or cook items, it is time to get a new microwave, since your old one is no longer working efficiently.
Listen while your microwave is running or cooking. If you hear a buzzing noise, your microwave's diode, triode, magnetron or high-voltage capacitor may be defective. Therefore, consider getting a new microwave.