My microwave is not heating. I found that one of the two fuses was blown. I checked the 3 door switches and they all work fine. I would just replace the unit, but it was almost $500 and is still in great condition.

The microwave runs fine outside of the fact that it does not heat. I replaced the blown fuse (250V, 20A). When I tried again, it made a loud groan for about 1-2 seconds then the groan stopped, yet it kept running. I assume it tried to heat for that 1-2 seconds, then the fuse popped again. I presume there is an issue with the transformer, diode, capacitor, etc. Any ideas which one?

Any help is appreciated.