"Cotter predicted the machines would be found "in somebody's trunk or someplace's closet."
Those will be machines "returned" that were actually used in the election, that real voters entered their votes on. They will not be counted.
"County workers will pick them up immediately after polls close and deliver them to the election warehouse."
So the continuity of control depends on moving "county workers". Simple enough. Some machines go into the back of somebody's SUV and other ones come out. Party workers have "voted" on the machines that come out - early and often. The non-returned machines then show up as the "found" ones.
Paperwork detailing which machine came from which precinct when will be "messed up", have "bureaucratic errors", which will be "straightened out" by oh-so conscientious county workers pretending exasperation.
Voila, the voters don't get to vote "the wrong way", and instead party activists "vote for them", the "right way".