I have a 2000 Ultra 150 that I bought new in 2000. This ski is great after I modified the heads. My problem just started. We have had the ski out 4 times this season and I have not had to add any oil. The oil level has not moved making me believe it is not getting oil. A growling/ possible grinding noise started and I promptly took it out of the water. I checked the hose from the bottom of the oil tank that leads into the machine (it runs freely when disconnected) I don't know where to go from here. Any suggestions would be great.