Happened before, eventually fixed itself, very odd.

Whatever setting I turn the dial to, it remains there at that exact spot and does not shut off or heat up. Just tumbles. This happened last winter. I hung clothes on line and used it to tumble only to soften. There was no heat. I had to stop it too or it would just keep tumbling. Maybe 6 months later it miraculously fixed itself. Dial completed cycle, heat, shut off automatically. Have used it for months. Now it is doing the very same thing. Any ideas what the issue is? It is an electric maytag dryer. MOD MEDC400VWO