Hi JR, Thanks for using our Forum. In 2002 we were using Jabsco toilets in the 377’s that we built. There is a macerator pump that empties the bowl. If it is still the original installation this pump may be compromised and be what is allowing water to get back into the toilet. Replacement pumps are available from Depco Pump in Clearwater, their telephone number is 800-446-1656. You can view them on the web at http://www.depcopump.com/index.php If you send your hull number I will do some research and let you know if there is any more information that may be helpful. Regards, Joe Brenna