The Kohler canister style toilet flushing system has a large yellow cap above the center guide that the fill tube attaches to. Trying to remove it without damaging the plastic components of this assembly took some time as I did not understand how it was attached until the parts were removed. I hope that by showing you how that cap is secured in place, you will know what needs to be done to remove it in your repair! (Wish Kohler had made that yellow cap much smaller in diameter so my fingers don't have to squeeze in between the cap and the canister...)