Envisage, I think the model number is not only on the UL(underwriters Lab) steel plate on the back. I think it is embossed on the top. I already knew that your model number was 400. I just didn't know if yours was 400A, 400B or just 400.
I know the size of the 400A is the same as the size of the 400. Does anyone know if there is any difference between the 400 and the 400A?