You can't always go by the manual - you need to get the model number right off the head - there should be a white label on top of the motor. If you bought the boat used, the manual may not necessarily be the correct one. But if it is indeed a Crown Head Centrifugal Discharge series, then you'll likely need to replace the CH50CW siphon bowl elbow. But first be sure that you're using the correct fluid in the tank. ONLY use Raritan "Concentrate" or raritan "CP - Cleans Potties," mixed 3 parts water to one part CP -- NOTHING ELSE!!! Other products may be too thick in consistency to work through the siphon system on the Crown Head. With the Raritan "Concentrate," mix it in the ratio of 2 oz. to 1/2 gallon of fresh water.