It happened before!:
In the following excerpt, smart poll workers took action in the first paragraph -- but unfortunately nobody did in the second paragraph. The machines in question were optical scans. NEW CHIPS could be the answer in places where eg: the exit polls don’t match the machine counts.
http://www.pww.org/article/articleview/4642/1/197A Nov. 7, 2002, Associated Press story datelined Snyder, Texas, reported, “A defective computer chip in the county’s optical scanner misread ballots Tuesday night and incorrectly tallied a landslide victory for Republicans.” Poll workers became suspicious. As a result of those workers’ inquiry, a new computer chip was flown to Snyder, Texas, from Dallas. Once the new chip was installed, the computer verified that the Democrat had won the election. The question remains: Was this an innocent computer glitch or something far more sinister, an attempt to steal that election for the Republicans?
In a July 30, 2003, article published by Alternet.org titled, “The Theft of Your Vote is Just a Chip Away,” writer Thom Hartmann reported on another “Texas anomaly.” In the November 2002 election in Comal County, Republican state Sen. Jeff Wentworth won with 18,181 votes, Republican Carter Casteel won a state House seat with 18,181 votes, and Judge Danny Scheel (a conservative) won his race with 18,181 votes. All three in the same county, same day, same year, all three with exactly the same number of votes. However, no poll workers in the county asked for a new chip.