OK update. Removed old microwave.
remove filter cover. Unscrew 2 long bolts. Remoce spacer bracket rear bottom of microwave.
Inside cabinet aboce microwave. Remove thin wood stip that is part of the shelf. Than remove the 4 screws that hold the mounting plate to the microwave cabinet.
This cabinet above the microwave also houses the HW switch and 12 volt circuit breakers. I removed the panel looking for bolts or screws that I thopught might hold microwave. But none there. This panel will have to be opened when I feed power cord back into cabinet anyway.
Now to repair or upgrade. Think time for new MH.