I maintain a Miprom 21 duplex from 93. The customer is complaining that intermittently the hall call buttons will start activating by them selves and the elevators start running to different floors and the doors will open and close and even shutter back and forth. I checked the card cage voltage which is 26 v dc. This does not have a separate group controller, only the cards for hall calls which are in both controlls. I have never seen this happen before but since multiple people have complained it must be happening. Does anyone have any ideas or suggestions? Thanks in advance.