It's six days until the American elections. Do you know whether your electronic voting machines are behaving?

The overwhelming majority of voters on Tuesday will encounter machines from Premier Election Systems, Hart InterCivic, Sequoia Voting Systems, or Election Systems and Software (ES&S). For your consideration, we present a roundup of problems currently known to be manifesting or to have recently manifested in testing and early voting, sorted by vendor.

• ES&S - The Omaha-based ES&S is, globally, the largest provider of election gear.

  Problems with vote-flipping on the ES&S iVotronic Touch Screen Voting System have been reported four states already in 2008: West Virginia, Tennessee, Texas, and Missouri. In many cases, it's suspected that the machines are poorly calibrated. The problem seems to crop up most frequently with straight-party tickets (that is, where one votes all-Democratic or all-Republican).

  The Brennan Center for Justice at New York University, concerned that the problems seem to be rather widespread, sent a letter to the secretaries of state in the 16 states where iVotronics are in use, strongly suggesting that the states follow West Virginia's lead and recalibrate their machines during early voting and before Tuesday's main event.

  Another iVotronics problem turned up in South Carolina, where voters discovered that choosing candidates in races where one is supposed to make multiple choices resulted in weirdness on the final-review screen, which the machine presents to voters as a last step before recording their picks. When multiple candidates are picked, the final screen notes only that there are multiple picks -- it doesn't say who. A pre-election fix for the flaw isn't possible at this point.

  ES&S was previously known as American Information Systems and was run by retiring Nebraska senator Chuck Hagel. Along with Diebold, the company faced a number of lawsuits in the wake of problems during the 2004 election.

• Hart InterCivic - The accessibility-friendly eSlate has, as previously reported here, flipped votes in some elections in Texas this year.
• Premier / Diebold - In August, Premier Election Solutions -- better known by its former name, Diebold -- has warned at least 1,750 voting jurisdictions around the country that their machines are in danger of dropping ballot totals for entire precincts.

  The problem rests with the tabulation software. According to the company, a logic error can cause votes queued to for counting to be dropped if more votes come into the queue -- a particular problem for larger precincts that might be using multiple memory cards during counts. The problem affects all 19 of the company's machine models, both touchscreen (DRE) and optical-scanning units.

  The problem was not a fresh revelation; it was originally revealed when various Ohio precincts spotted bad vote counts. The company first blamed anti-virus software and "human error," but further testing by Ohio elections officials and in-house high-volume testing at Premier confirmed that the problem lay in the software.

  According to Premier, the bug has been in force for about a decade.

• Sequoia - Testing results on Sequoia machines are at the center of conflict in New Jersey over the results of independent evaluation of the company's AVC Advantage touch-screen units. BetaNews reported previously on a judicial holdup in releasing the report. The report has since been released to the public.

  Researchers concluded that the AVC Advantage can be hacked in just seven minutes by swapping out either of two chips; the hack could also be propagated as a firmware change on audio-ballot cartridges, and a would-be hacker needs neither advanced training not full access to the source code to do the job.

  Sequoia disputed the findings, claiming unreasonable testing conditions and inappropriate machine configuration.