You're referring to the round skimmer cover plate on the decking correct? If so, and assuming you've tried the standard cleaning of the skimmer mating area and the lid itself, you might try gently rubbing the lid mating surface (lip area) with some fine 600-1000 grit wet/dry sandpaper. Very gently go around that edge and that may be all you need to help it slip back down easily.
If you don't have the wet/dry sandpaper I mentioned above, you can dry a Magic Eraser. It's a little more abrasive than a cloth, but in a friendly way.
Hello , This thread has been inactive for over 60 days. New postings here are unlikely to be seen or responded to by other members. For better visibility, consider Starting A New Thread.
Welcome to TFP! For a wealth of pool care information please check out our free Pool School. If you are in need of specific help then we encourage you to Register and ask us here in the forum!