Terribly loud steady warning noise on 2000 Nitro 205 sport. 150 mercury xr6 nitro series motor. 50 hours or less on motor. New block in 2009. Warning goes off only while under load. 5 passengers and tubing for example. 2-3 people and running hard is fine. checked oil res in lower deck and it was low. I added 2 quarts and it still will have the steady alarm under load. I have never had a warning go off before. So far I found it could be a magnet on the float in oil res. Not sure if this is in the lower res or the one on the motor. Oil res on motor is full. Any other ideas on what this may be? Runs fine, steady stream of water. Water pump replaced when block was replaced. Hole shots are perfect and planes quickly. No loss of power. No strange noises. Starts fine. Thanks for any input you may have. Stuff like this really bothers me when I can not figure it out!!!!!