First of all, I would bet your model number is 721.64683300 not 731.64683300, right?
The F9 problem in this microwave is a bad magnetron or inverter.
From other users:
"F-9 on this microwave IS inverter related. My problem was the magnatron and checked out bad with the help of (the tech sheet). It would run for a few seconds making clicks and then say F-9. It has been working great since I replaced the magnatron."
"f9 Kenmore Elite 36 " over tne counter microwave is supplied by LG made by Gold Star, made in China. It's main problem is the high voltage inverter board supplyed by Sears Parts. If you get a F-9 code on your microwave display screen and the micro quits it's probably this board. Reset the machine by pulling the power plug and waiting an hour. If it is the high voltage board is at fault it will probably fail after 45 seconds of start up. This part is really hard to get at but is less than $100. A qualified technician should be able to remove and repair this item in less than hour. Some techs will quote you $300 labor, don't buy it, it should cost a $100 or less. No need to buy another microwave."The
first thing I would suggest is a hard reset. Unplug the unit for several minutes or so. Then plug it back in, set the clock and try again.If it fails again and you or someone you
decide to look into it further, we have critical safety information and
disassembly information at our site, and our link is at our listing here on FixYa.
should be a "mini-manual" (tech sheet) hidden inside the unit
control panel or hidden on the left side behind the grille, which is
very helpful when troubleshooting, testing, and locating components.
our Web site, we have a video
available showing how to remove a typical
over the range control panel assembly in under 5 minutes.
You can find
exploded views and order parts by entering your model number at the Sears
The magnetron probably has an extended warranty beyond the normal one year parts and labor warranty.
So I would consult your owner's manual or contact Sears for details on the warranty.To get your owner's manual, just enter your full
model number at the Sears
On the resulting page, look to the right for the blue "View Manuals"
That Sears-related site has many free manuals. While the manuals they
list there are all free, they will ask you to register.
If yours is not listed there for free, you would have to order it
through the Sears
happy to help you with free advice and we'd appreciate your
thoughtful rating of our answer.