Even though there is no thread on this...since this site was helpful in getting my microwave working. Wanted to let others know, hoping it will help others...your unit may or may not have same situation so YMMV.
Microwave was doing all the normal unit should do except heating.
In my case it turnout to be bad Diode. When i tested diode using 9 v battery/multimeter, it tested correctly however, only odd thing was that black paint like coating was on leads so i changed diode even though it tested good under low voltage (using 9v battery) ... and sure enough microwave started working fine.
BTW, rest of the component testing procedures defined in service manual for magnetron. door switches, high voltage transformer did matched correctly except hi- voltage winding to the ground should be 50-80ohms not 0 ohm as stated in Kitchenaid repair/service manual.
Here is expected/suggested measurements for good component.
1 – Removed all wires to the terminals.
2 – Measured resistance (R x 1) from one term to the other = 0+ ohms.
3 – Reversed leads from above, still 0+ ohms.
4 – Measured resistance (R x 1K) from each terminal to housing = infinity.
5 – Visually inspected the unit and it looks ok. Some of the fins are discolored (brown and gold) due to heat/burning. The rest look new bright silver.
1 – Disconnected all wires.
2 – Measured resistance (R x 1) between the three Primary Terminals = .2, 0+, .2 ohms.
3 – Measured resistance between the two orange leads (filament) = 0+ ohms.
4 – Measured resistance between each terminal and chassis = infinity.
5 – Measured resistance from yellow secondary to chassis = about 70.8 ohms.
1 – Measured resistance (R x 1K) between the two terminals:
Initial reading = infinity
Swapped leads = High level resistance, then faded to infinity
Swapped leads again = High level resistance, then faded to infinity
2 – Measured both leads to metal case = infinity for both.