I guess the most "promising" way of tampering with the elections would be trying to mess with the final counting - when they total all the polling stations.
After the last voting, the machine prints a summary with the number of votes of each candidate. The printed list then is fixed outside the voting area to the public. The parties have people to inform the votes of each machine to their central. So, even before the final count is finished, the candidates know how many votes they have.
Slashdot Mirror
I guess the most "promising" way of tampering with the elections would be trying to mess with the final counting - when they total all the polling stations.
After the last voting, the machine prints a summary with the number of votes of each candidate. The printed list then is fixed outside the voting area to the public. The parties have people to inform the votes of each machine to their central. So, even before the final count is finished, the candidates know how many votes they have.
It saves a lot of time. In Brazil, the election results are known in the evening of the election day.