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Responding to SpaTech...My nomenclature was bad. It is not the diverter I am having trouble with, it is the venturi valve. To further define the issue, full travel in the clockwise direction should produce a stream of water with no air in it. Full counterclockwise travel would put full air saturation in the water. There is some slipping going on within the valve which does not allow me to control the flow of air into the water. I also do have a grit-getter and my spa is free from debris.Jeff