Push down the top with your thumb and use your water pump pliers to bend the tabs back. Please see image one below. You will first bend from the opposing corner as you see me doing. And next you will adjust your water pump pliers and bend from top to bottom to close the tabs as you see me doing in image 2 below. Switch is back together, but we still have one problem left. The dash light dimmer. First, using a small screwdriver carefully lift up the rotator piece as you see me doing in image 3 below. Next, slip a piece of 320 grit sandpaper under the rotator and remove your screwdriver. You can see this in image 4 below. Rotate your knob back and forth a bit (shouldn't take more than 6 or so times) to break up any oxidation, dirt, etc.
And now this fellow is finished and this one feels just like brand new...image 5 below. Hope this is helpful
~ Jon 1952 1/2 ton with 1959 235 | T5 with 3.07 rear end