To make it more secure I have removed the original pin and replaced it with a stronger bolt and flat nut. The bolt is the exact length so it doesn't stick into my hand and I have secured the nut with super glue. In the picture below the right fan has the new bolt, the left the original.
I have made the fans tighter than when they arrived and I find this makes them easier to use. I have also labelled the fans right & left for easy use. If your fans were not right and left when you bought them, you can remove the bolt and swap the wooden ribs over.