Our 4 year old KithchenAID gas range Off button will not respond when pressed. Only way to turn off the range is to unplug from the wall. All other buttons appear to be working fine. I'm thinking I need a new touchpad. Is there any way to test - maybe with a multimeter. I think the limited warranty will cover a new part but not labor to install. Does anyone have a idea if this would fall under warranty coverage?