Sounds like what is wrong with my Amanda microwave. What is approximate cost to repair? Is it cheaper to replace?

A hollow point star drive is what you need for them screws.
Getting a reading is another way of checking to see if we have an open circuit. Electricity cannot travel along an open circuit and therefore the appliance won't heat. This diode and this capacitor are 2 of the toughest stumpers known to mankind when comes to testing them. The capacitor could have simply seperated internally and died (I think that is the problem by the way) But the diode may be faulty as well. If the capacitor was shorted then the fuse would be blown. But the microwave runs so it is probably open. Their are several hi limit fuses built into this microwave beyond the power supply. One is hidden way on the backside of the cabinet follow the wires to it. If it is open then the mag(magnetron) aint getting power. The Mag has a fuse mounted on it as well. If the mag itself is open ther will be no heat. Look at the tower on the mag. If it has a hole in it then it is the mag. If the leads to the magnetron are shorted to the mag then it won't heat but the fuse will blow. So it probably AIN'T the mag. Take a note of how the cabinet screws come out. Put the long one in the same hole when putting the case back on or it won't run. These tricky dudes put in a switch which gets pushed against by a long screw and it is all hidden. Confused yet:D ?

You could have a bad capacitor or diode. If the cap is open or the diode is closed or both, then this could be the problem. You should get a reading on the cap but not on the diode. If the diode fails then you will get a reading. The capacitor stores the energy being produced by the transformer while the diode makes and breaks that connection about a billion times per second. This causes the magnetron to agitate the molecules on whatever food or bev you have in the oven. The constant agitation produces friction, friction produces heat.