Replacement is the way of the world with microwaves.
A microwave oven story: Back in the infancy of microwave ovens, my wife and I purchased an Amana Radar range oven. It failed almost exactly 15 years from the date of purchase. While we were shopping for a replacement, I happened to converse with a sales person about electronics. I mentioned that 15 years was kind of short for something built as well as the Amana and the price. "Sure", he said, "and your new Sharp Carousel won't last any longer, probably less due to mfg. process and quality control. Just look at the price, though. The Sharp is 1/4 of what you paid for the Amana". I couldn't argue with his reasoning but I'm happy to say that the Sharp is still working at least 10 years from date of purchase. Sometimes, you just get lucky.