Do you have a 160 S-Class or a D160R SummaCut? There was never a D160SE.
If you are shure your plotter is a 160 who thinks it is a 140, boot Summa Cutter Control with shift key pressed. Then you will find a Menu Item "Machine Type" in one of the menus.
If you have a SummaCut-R (and only then), you could check if the OPOS-Sensor is in place. Sometimes, on this machines, it snaps slightly out of his holder, what could lead to symptoms you have described.