Greetings everyone, I post here since AK has many people familiar with principles of microwave emission. My belowed home microwave oven, Samsung mt1066sb, broke today after 7 years of service. It doesn’t heat anything in the microwave mode, just make a strong buzzing sound which hasn’t been there before. All display functions work and the turntable rotates. The Samsung has built-in grills, they continue to heat and are controlled by timer as before; importantly, no buzzing sound is heard in the grill mode. I opened the oven and didn’t see any gross damages, blackened parts or bad connections. Since this oven works as a conventional grill (i.e. bake, broil etc) and only microwave “part’ is broken, I would like to fix it (especially if one takes into account that replacement is around $250 and is available only online). Internet searches points at a faulty magnetron as the most likely source of this problem. Samsung magnetrons are available at epay (new) for around $50 and replacement looks pretty straightforward. However, I don’t know what might be a reason for a magnetron going bad and how one can test magnetrons. Could it be that some component connected to the magnetron went bad and this cause the oven malfunction or killed the magnetron? I noticed a HUGE transformer inside the microwave oven which probably powers the magnetron; could it be shorted? Any advices of those who changed magnetrons, diagnosed or fixed microwave ovens or just opinion on this subject is greatly appreciated.