I have a Hayward skimmer that was installed 1978. I need to replace the weir doors which measure 9x4.5 in. If I cannot find the exact measurement on a replacement, can the door be cut to fit? I see a door that measures 8.75 x 5, which means that I would have a little gap on the sides, but the height is 1/2 in too big. Could I cut off the edge?