I couldn't find really tiny o-rings at my local home depot, but i did notice a little keychain screwdriver on an endcap that 2 tiny 0-rings on it.
Each one of these will "fix" two kayfuns
Amazon.com: Eyeglasses,Cellular phones,Watches Mini Screwdriver On Key Chain: Health & Personal Care
Just pull the little o-rings off the screwdriver and use them on the fill screw. The fill screw will not sit all the way flush, it sticks out about half a millimeter. No more leaks!
Each one of these will "fix" two kayfuns
Amazon.com: Eyeglasses,Cellular phones,Watches Mini Screwdriver On Key Chain: Health & Personal Care
Just pull the little o-rings off the screwdriver and use them on the fill screw. The fill screw will not sit all the way flush, it sticks out about half a millimeter. No more leaks!