The Princeton Study on Diebold election machines.
I cannot stress how utterly useless these machines are in a real election. Any election (past, present or future) that uses these machines is simply NOT VALID. The machines are far too easy to hack, and have been designed with deliberate backdoors in the code to make it possible to change election results without any trace.
If you are offered a Diebold machine to vote on, insist on paper. Voting on a Diebold machine is simply not voting at all.