The priest puts his head on the block; they pull the rope and nothing happens. He declares that he's been saved by divine intervention, so he's let go.
The lawyer is put on the block, and again the rope doesn't release the blade. He claims he can't be executed twice for the same crime and he is set free too.
They grab the engineer and shove his head into the guillotine, he looks up at the release mechanism and says, "Wait a minute, I see your problem......"