Hello, I am going to replace the original skimmer weir door with a spring-loaded generic model. Since I cannot find a door with the correct height I thought I'd fill the gap below the replacement door and the bottom of the skimmer housing with a piece of plastic wedged between the sides of the skimmer housing. My question is how do I determine the position of the bottom of the replacement door so that it functions properly. I cannot remember how the original door (that was bolted into the concrete at the bottom of the skimmer housing) looked both with the pump on and off. I hope I have made myself clear. thank you.