Noticed electrical burning smell last week then stopped working. Thru breaker to insert. It is a 2008 Mt Vernon AE insert. Opened up and found ac output was melted at power supply. So hot it also melted part of ac input and wall control wires. Anyone know why this could happen? My dealer has not been of help. No other issues noted before. Control board and firepot were replaced in 2009. Don't want replace parts unless l know cause.