Richard, I have had this problem happen twice, the last time today. The heater woke me early this morning making this loud noise. If your heater is out of warranty good luck the company is no help they will sell you and insert.
First, if this is the case and they tell you it voids your warranty, so what, you don't have one anyway.
Place the heater face down on a soft surface. Unscrew the 4 screws inside the back then bend back toward the insert all 4 brackets, they will bend easily. Then lift off the expensive mantel cabinet. Then remove all 10 screws along the top. Carefully remove the top because it has a electrical connection that you do not want to disturb. You will see the fan behind the element. What I discovered this second time. The noise on mine was so loud this second time that you couldn't stand to be in the room with it.
Okay, now look to the left side of the fan you will see a black rubber whatever you call it. Be careful, plug in the heater and turn it on. Place you finger and press onto the end of the black plug push firmly if the noise stops that 's your problem. There is nothing to this simply made heater. I kept at it until I figured it out. At first I thought it was a bearing or something so simple because the noise was only coming from the fan itself.
Okay, Remove the black rubber cap, if pressing firmly on it in the center stopped the noise. You will see the rod that goes to the motor on the other end of the fan. Obviously slack had developed on the rod. I tried pushing it and hammering back in. Didn't work. so I took the copper piece that held the rod out and a small washer the size of the piece behind it. Then on the rod I place
two small but a little larger washers. Replace the black rubber cap. This took up looseness that was in the fan making the noise. So for now it is working properly again. For how long? It was a nice gift just hate my mother fell for this.
Sylvia Franks, January 2011