I have an in ground sp/pool, 1800 gallons with all Pentair equipment. It was installed in the mid '80s, so no information from the installer available. In the past few years, 3 of the 6 return jets have stopped working. I found an old post here that said the venturi jets are removable, but they are 10" inside the returns, so I cannot see what I am doing. With a long extention, I am able to get a 1/2 inch socket onto them, but I don't think they unscrew because they just spin. I am aware there is also a snap in variety, but how on earth would you get them out of the venturi tee???