The same thing happened about two years ago and when I took off the back cover, the high limit switch was melted and crumbling, so I replaced it and it's worked fine until a couple of weeks ago. We smelled a stinky electrical burning smell a couple of times and then it stopped heating past 250 degrees. Turns out the high limit switch was crumbling again. This time I replaced both the high limit switch and the bottom element and it heats up again like it should to any temperature. One of the connector wires to the element was half broken, so it took some time to cut that and reconnect it to the same butt connector.