My hayward navigator is not moving when at the pool floor. Could it be the gear box needs replacing? It has several new parts and I checked the suction, which is perfect. When I lift the navigator up toward the top of the water level the wings are flapping and the feet are rocking and there is nothing blocking the suction. When I let the vacuum drop to the pool floor it isn't moving and I don't see the wings moving. The gear box has not been replaced. At a pool store I looked at it with a salesperson, and it was not making the "whizzing" or "whirring" sound. I disassembled it, re-assembled it, and it makes the whizzing sound now. All the parts inside look fine...I've never had this particular problem before.