Flame light problem shutting off?

My heat surge blows fine but when I shut it off, the flame freezes and doesn't go out. I entered through the bottom front panel and turned the cyliner that works the flame, also replaced a bulb. Didn't work, have also tried reset, and tilting it from side to side and laying down the front on a 45 degree angle for 15 seconds, as recommended. We have to unplug it after we shut the heat off to get the flame light out. Any suggestions?