Sorry, should've been a bit more specific, but was afraid to as my initial post was already pretty long...
The brewer uses both the two-phase (208, fed by two legs of a three-phase system) and single phase (120) power, and so requires the neutral to carry current back from the 120 components...
I install and repair coffee and espresso equipment and we sometimes run into electrical problems beyond my knowledge (well versed in household wiring, good with fundamental applications of ohms law, etc. but I'm no physics major!) The issue that comes up most often is dubious grounds, or...