In the production process, sometimes the knife bed cannot be lowered and the paper cutter cannot cut normally. At the same time, the photoelectric sensor control device also fails. At this time, if all the power is disconnected and then turned on again, the photoelectric sensor control device can work normally and the paper cutter can also be lowered, but the same failure will occur again after a period of work. In this way, it is possible that the electromagnetic switch of the machine has failed. As long as the electromagnetic switch of the same specification is replaced, normal cutting work can be quickly restored.