When you look at these seadoo motors they all have 2 or 3 piece exhaust, on most are rubber "donuts" in the larger pipe and yours may be decayed or vibrated away to the seawater, compare your model pictures to your other model - it looks like you have a flat top and a tilted motor xp800 - same ideas that Bill suggested, the motor has to stay down in the hull or anything will get torn loose.