Windshield wiper popping off

[cfriedman67]

I got caught in some rain the other day and my windshield wiper popped off. I got lucky and got it off the road, popped it back on and the same thing happened shortly after. I have read other people have used a set screw to secure the wiper arm by drilling through the round part of the wiper arm that attaches to the wiper piece that sticks out of the body by the hood. My question is does the set screw get drilled into the round piece that sticks out of the car or does the set screw push up against it like with the spinners on our wheels? Any other suggestions are welcome as well.

thanks Craig