How are you using them. MWOs should last many years if treated correctly. Most important rule is never run the MWO with nothing in it. It causes overheating of the magnetron and premature failure. I have been using Combination MWOs since the mid 70s and in all that time only one has ever failed on me. I have used Brother, Panasonic and Samsung without problems. The one that failed was a Brother one that lasted over 20 years.
The Evil Within 2 review-in-progress