C5300 code. Kyocera rep said to check the door switches for 5v. I replaced both front door switches. This problem is sparatic but enough to interrupt the office where it is. I am going to change the drum unit and main charge, The next thing the book says is engine board but before I do that has anyone dealt with this?

Check the switch for the left side door. Make sure the actuator is hitting the switch when the door is closed. We have had to adjust that actuator on previous models that would cause c-codes.