My boat is a 2000 Hunter 420. I often lose prime ... causing inability to draw water (for sink, heads)...the pump runs endlessly. I have tried a solution that has worked in the past: open all water valves, including the stern outside shower, all to no avail. I have checked that my 3 water tanks have water levels at full or at least above half full. And repair agency suggested it is because the pump is "above water level"...it's located under the starboard dining table seating and just forward of the nav table. The agency is suggesting relocating the pump below water (sea) level. It's hard to believe Hunter misplaced the water pump and the it needs to be moved. That would involve a great amount of re-piping. Any suggestions for regaining prime?