I examined the power cord in the junction box more closely. This unit, that we had installed by a big box store, had a flat (zip) cord that doesn't strip like normal sheathed romex. I found that the installers had nicked the neutral and simply wrapped electircial tape over it, yet with some bare copper wire showing. I pulled it all apart, carefully cut the bad section out and stripped (carefully) the sheathing for each line. Reconnected and she runs fine. I did purchase a heater element (this was the manual's diagnosis using the service mode), and a flood switch just in case (this reportedly contains a thermistor)-btw this latter part did not match the flood switch design on my unit, a GE GDF610 model. Lesson here is to check those electrical connections first! Hope this helps someone.