Can’t find another way? Can you draw a couple circles? The OD is 8.5”. Cut a circle of aluminum, plexiglas, your choice. Trace it on the floor. Trace your 7.5” circle inside, 1/2” inside of the first one. That’s your cut line. Do your pump work. Glue you 8.5” in place as a temp repair. Buy the G8 cover when it comes available.