Remove the two nozzles closest to the debris collection with your removal tool, and physically inspect the pop-up head for damage. Specifically, check the orifice for any obstructions. If there aren't any obstructions, manually ratchet each nozzle 360 degrees, by popping it up and down to mimic its operation in the pool. If it does NOT rotate, the nozzle is broken and you will need to purchase a new AA Nozzle.