There are multiple stories of electronic voting machines changing the vote on the screen. The voter corrects it, and the correct ballot is printed. But, if the voter misses the change, then an incorrect ballot is printed. Sometimes, the voter has to correct it more than once.
Here in New Hampshire, we use paper ballots marked with a felt tip pen. They are scanned with an optical reader, but it's straightforward to do a manual recount of the official paper ballots.
Electronic balloting machines are an invitation to programmatic fraud.
I attended a Free Software Foundation annual meeting some years ago. The assembled group was asked whether they preferred electronic voting systems over paper ballots. Not a single hand went up.