I used to hate the caps, now I like them. The trouble occurs when you open the oil or gas tank and in doing so you turn the cap past its open position. That is, the top part of the cap twists to its closed position like when it is locked on the neck of the tank. Then when you try to get it on, it won't catch the nub to lock down. I found the easy solution to this problem accidently: I was trying to strangle the cap out of frustration and it flipped back into its open position and went back on without a problem. So, when your cap won't sock up, simply grab the lower stem and twist the upper part whichever way it will go. It will open and you'll be able to pop it back on without a problem. Now go out to your garage, grab your Stihl and try it. You'll be glad you did.