They have the proper type of pan.
Transformer finally came but was not the cause of the noise. Noise is from the Blower motor/fan that gets louder as it is on longer. Not heat related as from the customers description.
Do have a second problem though. The burners do not heat as fast as they did at first (quart of water to boiling in 1 1/2 mins, it now takes 2 -2 1/2 mins).
They had this problem once before still under factory warranty, inverter boards were replaced? Not sure from the wiring diagram if the "power board' is in that circuit also, or not related.
Issue now is performance, just not sure where the power stops