I have checked the wiper dwell switch at one of our specialist testers today and find that the one we supply is as per an original switch . You can see from the photos that the knob goes right through the clear plastic, and is not held in place by the plastic. We laid our plate over the original and our hole is the exact same size. The replacement cover fitted perfectly to the switch.P5020019A.jpgP5020020A.jpgP5020021a.jpg