The toaster no longer toasts..the filament is broken.

I too have the same KCO223 countertop toaster oven, and the toast function is not working. All other functions work fine, but the blue light won't come on in the TOAST mode setting.

https://toasteroven.info/toaster-oven/toast-in-toaster-oven/

https://sensiohome.com/collections/kitchen-appliances

1500 watt six slice toaster oven. 450 degrees for toast, darkness level 4. Both timer and temp knob must be on. Time range varies. low fan level.

Your timer is broken, kind of like mechanical watches and grandfather clocks, and music boxes.... If you over wind they no longer work properly or at all. The coild that stops and starsts it doesnt lock any more and now it doesn't know when it is technically done. SO my dear, you now have the best, awkward toaster oven :]

Chances are very slim your toaster oven is repairable anyway if the heating element burns out. A replacement part is not available, and there's no way to reliably repair a break. Even if it could be fixed, the low replacement cost makes it uneconomical. Parts and labor would run close to $50, maybe even exceed that price.

Unless you can find a part and do the repair yourself, small appliances today are throw-away items.

the elements can be replace, BUT, it is just not cost effective. you can buy a new toaster for less the the cost of repair.

The problem is 4 capacitors on the small circuit boards inside. Three 220uf 16V and one 1uf 50v. These apprear to be going bad from internal heat drying them out and they fail. Symptoms include toast will not start when button pressed, or does start but then stops soon after. A buzz or hum heard when the Toast selection is made..(you should hear nothing until the start button is pressed) and the timer beeper no longer working. These are about $2 in parts, and easy for a good electronics person.

Your selector switch may be broken if the oven works on selections other than toast.

there not replaceable . metal straps are welded to the ends to make the electral connections . thats why there are no elements for this oven , sorry factory-store-home-dump AS FAST AS WE CAN

I don't know if you can fix it but if you are good at basic diagnosis you can take off the right side and see if the toast latch is broken or perhaps out of place. This type of unit is not so easy to take apart and put back together. The parts fit is a bit strange.

I found that the heating element in the top front was burned off at the end. I removed the side cover and the ceramic insulator from the broken end. I then grabbed the broken end of the spring inside the glass tube and stretched it to where I could re-attach it to the connector. It now works after getting it back together.
If you attempt this repair, UNPLUG THE OVEN FIRST!
There is also a security screw at the bottom of the side cover.