Sand is blowing back into my pool through the returns, so I want to take apart the multiport valve to check it. My valve is made by VRAC and has no screws. It looks like maybe the upper plastic part screws onto the lower part. The top part has notches around the perimeter. It looks like maybe the idea is to tap those with a hammer and screwdriver to remove the top part -- but I'd like some assurance before I do that, so I don't break anything.