The stove started making a high pitched, squealing noise coming from the back of the stove, this afternoon. Shut it down and did a good cleaning. Was sure to clean the fan behind the wall on the right, inside stove and got her squeaky clean. As I fired here back up, the noise went on for five minutes, regardless of the fan speed and then tapered off. Comes back on and off, intermittently but seems like something is "going". Any ideas? Pellets are dropping the stove is running and heat is emanating but something isn't right....