The author of this short article , a well respected expert in election security, writes, “Based on preliminary reports published by the team of experts that New Hampshire engaged to examine an election discrepancy, it appears that a buildup of dust in the read heads of optical-scan voting machines (possibly over several years of use) can cause paper-fold lines in absentee ballots to be interpreted as votes.”
Read the comments, too. This one stands out:
“I recall a conversation (by phone) with a local election administrator in another state who used the AccuVote OS [a scanner] in her jurisdiction. I asked her about preventative maintenance. She said 'what do you mean?' I explained how paper sheds fibers, dust, and fingerprints accumulate on things people touch, making a layer of crud. Cleaning this off matters. She seemed quite surprised. I asked if she had a service contract for the machines. She said it had been dropped years ago because it was too expensive.
In conversations with other election officials when asking about mark sensing, I have frequently heard the line: 'These machines are certified to rigorous federal standards, so we don’t worry about that.' Unfortunately, this misrepresents the standards. What the standards guarantee is that, in principal, if adjusted and maintained appropriately, the machines can distinguish votes from non-votes (including folds). It is up to the administrator to do that adjustment and maintenance. Without it, the standards are irrelevant.”