You may not know that the finger looking part over the fire-pot is a thermocouple. The ceramic cover keeps the direct heat off of the sensor while underneath is a braided wire. It's purpose is to determine the amount of heat within the stove and its stages of startup and shutdown. Note this does not control the convection blower (Fan that comes on to blow heat across the room). Symptoms of a bad thermocouple include not starting, shutting down after start up and over feeding. The first step to troubleshooting the problem is to check the end of the braided wire by removing the cover. The thermocouple could have cracked where the braid is soldered at the end. Next we must locate the control box on you model stove.
Above is a newer style control box. Older versions are not a clear plastic. They are always located near the reset button. Some Classic Bay 1200 FS stoves have their control box inside the hopper. Other stoves they are behind a side panel. When plugging in your stove, the clear plastic boxes will flash blue. Count the blue flashes to see which setting the box is on. The box will then quickly flash orange to test the thermocouple. If it remains orange, there is no continuity and the thermocouple is bad. Old and new style boxes have both a Red and Green LED light. In the new style boxes, the LED illuminate the whole box while the old style have small LEDs on the top of the box. During startup the stove will drop pellets and ignite. Not until the thermocouple senses heat will the Green LED turn on and the stove will begin to feed more pellets. If the sensor does not read temperatures higher than those producing the Green light, over feeding will occur. Once a normal operating temperature is reached, the Red LED will light. On shut down, the LEDs will turn off along with the exhaust blower.
Remember to inspect the thermocouple cover while cleaning. If light shines though the cover it need to be replaced.