Hi, we just recently changed the sand in our S244T Hayward Sand Filter, parts were spread out for a few days on the ground before putting it back together, came across this part and do not remember seeing it and have no idea where it goes. looked at online manual and parts diagram and its not listed. Any ideas? It appears to be a lid, it reads 'Tighten' with an arrow and 'Loosen' with and arrow and 'Do Not Discard'. My husband put sand filter back together without this piece since we couldn't locate an area for it to go, but I feel it needs to be in there somewhere, but I guess it could possibly be from something else but not sure what. Any help would be greatly appreciated. View attachment 62302