I do not have a drawing, nor do I have photos. But the siphon was working well prior to last summer and I know of no changes to the system during or since that time. I wondered if a piece of the PVC had merely cracked for some reason allowing air to enter between the outlet, where we capped it, and the horizontal run of pipe through the dam. The system is a 6in PVC system with a 90 elbow at the end of the outlet pipe. But again nothing new that would explain the change since last summer that I know about.