Wasn't the problem with the ice-maker, that the spark plugs were
fouling-out?
And, didn't the plugs eventually burn up from the fouling? After being
cleaned numerous times?

the "plugs" cited were for the engine. The author was adding "color" and
didn't know that diesel engines don't have plugs. Neither did his editors, at
least for the first edition. I assume the error was corrected in later
editions.