I have the same microwave and have the same problem..f-9 displayed and uncooked food. This doesn't happen all the time for me. Sometimes the food does cook like it should but more often lately it hasn't been cooking.If you find out the problem e-mail me at wagsjd@insightbb.com
I would appreciate it.

I found a post on another site that stated an F-9 was a door switch problem. So when I disassembled the door jamb to get at the switches I found the Tech sheet. It states that the F-9 error code is probably the inverter. But first you have to unplug the unit for 40 sec. to see if that clears the problem. If that doesn't do it, then you should check the thermostat for continuity. But according to the schematic, if you don't have continuity through the thermostat there would be no power to the unit at all. I have a service call coming to replace the inverter. It's buried inside the unit. I'll post again after the tech comes out.