Here is one of what will unfortunately probably be many videos of a voting machine not accurately recording a vote.
What should you do if you have a problem at the polls? Here is information from the Federal Election Commission web site:
Where do I Report Suspected Election Fraud?
The first step individuals should take to report voter fraud or voter registration fraud is to contact their state's main election office.
Federal authorities may become involved in election fraud matters when a state prosecutor asks for federal assistance. In cases where intimidation, coercion or threats are made, or attempts to intimidate, threaten or coerce are made to any person for voting or attempting to vote, federal civil voting rights claims may be brought by the Voting Section of the Civil Rights Division within the Department of Justice (DOJ).
If you have information about voter fraud and/or voter registration fraud, you may also contact the nearest office of the Federal Bureau of Investigation (FBI), local U.S. Attorney's office or the Public Integrity Section of the Criminal Division within the DOJ
Where Do I Report Suspected Voter Intimidation?
Laws on voter intimidation are administered by the Voting Section of the Civil Rights Division of the Department of Justice, which can be contacted at 800/253-3931.
Other resources for reporting voting machine malfunctions: 1-866-OUR-VOTE and http://www.truethevote.org/