Hmm....from the evidence I've seen, most of the tampering comes with paper ballots. The easiest and most popular is marking and inserting paper ballots into the voting box before the polls even open, or to "run out" of ballots before the polls close and then "bring in more" many of which conveniently happen already to be marked. This is difficult if not impossible to prove since so many different people could have done it, and also because the people who are supposed to police the polls also are complicit (like the Democrat attorney general is going to investigate the Democrat secretary of state over an election won by the new Democrat governor? yeah, right....). A similar method involves having people enter the voting booth with several ballots in their pocket which they then pull out and slide into the ballot box along with the legitimate original. Again, nearly impossible to prove. (absence of proof is not proof of absence). If you hang out in the right circles with the right people and slip a few drinks into them and then get them reminiscing about the old days, it can be quite instructive, even if the statute of limitations has long expired.