I've got a km-c4035e that states to "add paper in casstte 1" I already tried to swap feed relay board and paper feed units,updated firmware and still have message.I checked for the correct voltages at the feed relay board and they are where they should be.Any other ideas?

check for paper in the connectors between the machine and the drawer(s) this is usually the problem, in the Falcon I there was a 24V loop that went through these connectors and if the paper got into the right spot, you would not get paper lift, or clutch drive because they used that same 24V line. Good luck

Is the machine lifting the paper to the paper empty switch? Is the lift motor running, if yes and yes have you tried sim 31 and checked the paper empty switch that way? All things that I would start with, sorry so elementary but your description is a little vague