I thought the Vaco might be missing a part. Probably still making it's way to the bottom of the bin I took the screwdriver from.
The sleeve on the second one is still there, it slides down just as described by papaw.
The 3rd one, the Hunter, I still don't really get. The spring inside is so stiff that you have to put a good 5-6 pounds of downward pressure on it to activate the device. Not good for screw starting I wouldn't think.
But hey, how 'bout that universal ... no comments from y'all, but I thought that was quite a find.