Report "On a Heidelberg Web 16 printing machine there is some web guide sensors & control units, alternatively called web-edge scanners. The first one is on the in-feed section of the machine & the second one is on the chill rolls. These electronic gadgets drive stepper motor which in turn help the operator to guide, manually or automatically, the paper through the printing units and folder. My problem is that as soon as you switch on the machine the stepper motors start jerking back and forth continuously. Unfortunately I don`t have any information about the sensors which are manufactured by WEKO for Heidelberg part number 5E110.1541A, Control Unit which is in 2 separate units part number 5E110.1521B, the other one is type BKR.1431. Assistance with information about these electronic controllers or where to get it will be greatly appreciated even suggestions solutions to the problem"